Hard to overstate how important a good profile is on OKC.
Mine is too long but it's hard to cut it down because it works really well on there.
First thing: pictures. You're going to want some decent ones. Ideally, your main picture should be a knees & up or maybe a bit or closer, with a clear view of your face, looking slightly off-camera as if you're seeing something interesting, with narrow depth-of-field. That means: your face/body in focus, the background a slight bit blurry. Soft/muted colors, not saturated. Ideally, something kind of like this:
http://images.thesartorialist.com/thumbnails/2013/10/92813robert4191web.jpg (ignore the fashion, just look at the technical aspects of that photograph). There are a lot of psychological tricks at work when doing this... the narrow focus depth of field creates an illusion of intimacy. Men looking slightly off camera creates curiosity (what's he looking at? A woman? Is she hotter than me? Why isn't he paying attention to me? Seriously, this sounds stupid but it works). When asked to crop to your face for the icon, keep it loose... enough that your face is big enough in the square that it's easily visible on the search results pages, but off center a bit and not too close so it stands out a little.
A psychological trick I use on
myself is using a main photo that clearly shows my flaws. I'm very self-conscious about my looks (basically, I'm a slightly taller Costanza). I make sure it's evident in my first shot. No need to waste time on women who will be turned off by my looks by trying to arrange a date with photos that hide it, then surprise them in person when we actually meet. It means I have to send out a lot more messages to get a reply, that's fine, but the replies I get are from women who are clearly OK with my looks and it completely makes it easier for me when the in-person meet actually happens.
Now, add five more photos. The classic action/having fun shots. I know it's cliche, but have one with a hot chick. I have a hot friend I teamed up with to run a scavenger hunt-like thing with, so I have a photo of her holding up my legs like a human wheelbarrow for one of the stunts we had to do. Me doing something stupid and looking goofy & having fun with a hot chick. Winner. Another one I lucked into... I was doing a photography Meetup at a stadium, we took some photos before the event, then I took a quick nap in the stands while waiting for the action to start. Some other photographer took a photo of me sleeping, all alone, nice muted colors, narrow-depth-of-field... score. Sleeping shots work for some reason. Another pair of cliche shots I have are the standard skydiving photo and the running shot from a 5K. Sign up for a 5K and make sure you pass each photographer. There's usually a way (check reddit) to get the photos for free off their websites

. Every shot should convey that you have an interesting life.
Then, the profile itself. Be funny. Make some jokes in there. Make yourself seem fun & interesting. Put in some random stuff. Good advice I read somewhere is write something every day for a few weeks in Word or whatever, for 20 minutes or so. Throw most of it away. But just get into that stream-of-consciousness mode when writing, then take one good bit and drop it in your profile somewhere. Just take one of those prompted sections and ignore it... just fill it with whatever you want. I took the "most private thing you're willing to admit" section and just wrote a story in there about something interesting that happened recently. With self-deprecating humor. (One day, I went to take in the garbage cans from the street, and I saw a purse was in one. Some thief must have dumped it. So I turned it in to the police. That's it. Turned it into 4 long paragraphs with 20+ jokes peppered in there, 15 of those at my own expense, and a nice call-back on the closing line. Took me a couple weeks to get into the zone to write it, but it's great. Doesn't answer the question at all but who cares? It's funny, it's interesting, and women have written me first because of it.)
Try to answer as many sections as you can with jokey answers. "I'm really good at:" is answered with "Fixing things. But it turns out I'm even better at breaking them." "Favorite Music: Classic rock. Like fine art, it's better once they're dead." I have an RFK assassination joke in my favorite foods section. Just random stupid stuff. I get a new message every month or so from some woman just saying I have the best profile they've ever read.
Edit often. Cut down as much as possible. Every sentence should be there for a reason and serve some sort of duty: is it funny? is it making you seem interesting? If it's not either of those, delete it or rephrase it.
Messages: I pull a hook move with my messages. Every girl I've ever met online, OKC or otherwise, has said the same thing: "You're the only guy who ever replied who actually read my profile." Secret is, I barely skim. They're all pretty much the same. You can often re-use bits of messages to other girls that have the same interests listed. Just pick two or three things in their profile and tell a quick personal story. Message of 5-8 sentences, tops, to open. "Hey. Saw you're a Doctor Who fan too! Did you check out the special preview at ComiCon? I got hooked on that show on PBS when I was a kid, remember that?" or whatever. My main hook: I like photography. I'm pretty good at it, or at least I like to think so. Had a couple of showings and been published on a lot of random places. I have a nice collection of shots I worked on with a photography meetup group. So I have a flickr account full of photos I've taken all over the city at a ton of different events. I find one thing they're interested in that I've taken a picture of, and send them a link. Women cannot resist this... they see one shot in my portfolio and end up scanning through the whole set. I'm doing this on purpose. I always get a message back "I had to just keep clicking, I love your pictures!" and stuff like that. That's the hook, something that leads elsewhere that adds interest. It's like added content to the original message. Sometimes it's a link to a newspaper article about me or something like that. There was a halloween zombie-walk for charity I went to take pictures of for fun one day. Every girl who mentions zombies or The Walking Dead in her profile, that's my excuse to send a link to my photos. And at least
half of women's profiles mention one of those, it seems. You'll start to notice this: the same 3 or 4 things keep showing up on every girl's profile. Find something to say about those things, make a nice catalog of form letters you can send out, slightly changing and personalizing each one, but, basically the same. I have "zombie message" and "football message" and "food trucks message" and "X-Files message" and one of those will work for like 90% of the women on there. Been a while, but I bet a good "I love Crazy Eyes on
Orange is the New Black" message will work on 75% of the profiles on OKC.
Another thing to do is spell check. Carefully. Be well-spoken. Be interesting. Work in "you're" and "your" casually but on purpose in the message so they know you're literate. Seriously, this actually is enough to make you stand out.
Anyway, it takes a while because I'm not good looking, but when I'm really working OKC I'll send out 5 messages a day to any one who could be interesting. I'm lucky to get one reply in a week, but it's a quality lead. Usually during my lunch break in my office, just take 20-30 minutes and crank out a few semi-personalized 5-8 line messages. It's all a numbers game.
It's been a while since I've been on OKC, but there's two other things I tried in the past that
may have been successful: 1) edit my profile every day. Make a very minor superficial change. Replace an "I've" with "I have" and then back again the next day or something. Change an ellipsis... to an em-dash-- somewhere in a short funny answer section (Like above, where I answered "Fixing things. But it turns out I'm even better at breaking them." the next day it'll read "Fixing things. But, it turns out, I'm even better at breaking them." and then I'll switch it back the next time I'm online). This puts your profile in the "Recent Activity" section of women's login pages in your search area. I don't know how well it works in generating interest, but why not try? 2) OK Cupid has a color-rating system. People who reply often are colored green. People who reply sometimes are yellow, and rarely are red.
Every guy on there is colored green, because no guy isn't going to respond to every message he gets. Except me. I'm yellow. It says "replies selectively" under my profile. How did I do this? Well, one by ignoring some messages I get. Two... the devious way, I created some fake women's accounts and emailed myself from them, then deleted the emails when I got them in my main account. Again, I don't know if it works on women or not, but why not try? At least it's one simple way to stand out when women are looking on the site. They see a results page with a hundred guys, all with the green mark, and one guy who's actually picky. How can they not be curious about that?
Best of luck. Just keep cranking the messages out. Eventually you'll see what works and what doesn't.
And don't get discouraged. The standard OKC mailbox can hold 300 messages before they ask you to upgrade to pay. Many women I talk to get 50-100 messages a day.
A day. Getting read in the first place is tough. When you have 100 messages waiting, most women just bulk delete. If they're talking to some guy already, bulk delete everything else. If they're having a bad hair day and aren't in the mood? Bulk delete all their messages. Fight with their mom yesterday? Bulk delete. Seriously. Don't take it personally. Don't worry if you've sent out messages to 50 different women with no replies. The odds are stacked against you. 1) You have to catch her on a day when you can get her attention. Not a day where she's cranky from work or had a fight with her roommate or is going out of town for the weekend and bulk-deleting her messages because she's not in the mood. 2) You have to fit whatever random 'type' she is interested in... tall guys, bearded guys, clean-shaven guys, tattoo guys, guys who look like her dad, guys who look like they'd piss off her dad, et cetera. 3) Your profile, as good as it may be, can't hit any of her triggers... Does your funny story involve the time you threw a birthday party for your dog, but she's allergic to dogs? Do you mention your love of 'Sons of Anarchy' but she dated this guy with a motorcycle in college once and now they're a huge turn-off for her? Are you vegan? Are you not vegan? Whatever random reason some woman comes up with, you have to luck into not matching any of her triggers, and then match something that
is a turn-on for her. Maybe she only messages guys back who list a foreign film or two on their profiles. Or, no foreign films. Whatever. The point is, the subset of the subset of the subset of women who will reply to a message from you is so small, you can't let it discourage you. Just getting a match at all is tough enough, just understand it and don't let it psych you out.
Hang in there and keep trying and keep learning.