It's pretty interesting how many different ways there are to skin the cat. That said, here's the principles I've followed in taking my team to the championship game in 9 out of the last 11 years in my 10-team league (2 protects).
1) As others have mentioned, comprehensively understand the rules of your league. If there are rule changes coming one thing I like to do is figure out what impact it would have had on the previous season. A few years back my league added 1 point per reception STARTING with the 6th reception - only for WRs and TEs. What I found was that while it did move up the numbers for some of the stud WRs, it really didn't do a ton to the relative value.
2) Look at past drafts in the giving league to try and uncover the tendencies of your fellow owners. I ALWAYS make my own labels and bring them to the draft and put them in books myself but great stuff like the draft dominator can serve the same purpose. The main point is that over a number of years you'll be able to look at past drafts and know "This league member almost always takes a TE early, this guy likes to wait on QB". Make a list of all of your draft picks and then figure out how many people at each position were gone by that point in past years. While it's true that you'll find variation from year to year, you'll generally get a much better feel for when and where the runs are likely to occur. It also enables you to figure out you might be your competition for that trendy rookie RB you've had your eye on.
3) If keepers are involved, I always do my best to figure out what the worst-case scenario protections would be from the other teams and plan accordingly. We protect 2 guys, so I already know to bounce anybody rated lower than 21 without a second thought. In practice the line is more like the top 15. Some years it's easier than others. This year I feel like I lucked out as I didn't protect Grant and managed to upgrade to Gore much to my surprise. Again, knowing your opponents' tendencies (so-and-so ALWAYS protects Manning) is again helpful here.
4) I agree with the maxim that you generally be the last guy to take a starting QB and the first to take a back-up QB. There sometimes are exceptions to the rule (especially if you think there's a huge dropoff between, say, the 7th QB and guys 8 through 14) but in most instances I find this to be good practice. I still remember the year I got "screwed" with being forced to take Michael Vick and he went on to play 16 weeks for me and lead me to a title (yeah I lucked out and that was the one good year).
5) I'm a huge believer in hammering the RBs. Much has been made of the increase in RBBC in the past couple of years. While this is true to some extent the simple fact is that WRs are in a committee situation all the time by definition. My leagues happen to have more emphasis on TDs and I just feel much more secure knowing that my lineup will have as many 25-touch players as possible in it.
6) With 5) in mind, targeting the bell-cow backs is also very important! Of the 5 RBs I drafted (all in the first 8 rounds), Gore, Forte, and SJax looked prime to carry the max load. Jacobs and MJD, while in committees, were clear goal-line guys. Clear #1 backs are a lot harder to get on the waiver wire IMO.
7) I personally have found that the sweet spot for WRs is right around the teens. Now in a keeper league I'm used to the stud guys basically always being gone. Beyond one or two guys, it really does become a crap-shoot and I generally don't see a lot of difference between the #1 receivers on about half the teams in the league. Look for good offenses. Look for mediocre teams that have some offensive talent but also may find themselves behind as often as not.
8) I've kicked myself every time I jumped on a "stud" TE being one of the first 2 to take one off the board. Conversely when I waited to the next-to-last round I almost always was pleasantly surprised. This year was an exception as I somehow got Witten as like the 7th TE out of 10 teams. Even with all the other rules I try to go by I must say - NEVER pass on a true talent that has slipped too far. A certainly flexibility helps.
9) I never see any reason to take a kicker earlier than the last round. It's always the easiest waiver spot to fill.
10) Summarizing the above, my typical draft usually sees me taking 3 RBs in the first 4 rounds. A good #1 receiver in the 3rd round. My QB in round 5 usually though sometimes in the 6th. My 4th RB in round 5 or 6 to make sure I get that last starter. My 2nd receiver, generally somebody solid though possibly not spectacular in round 7.
11) I ALWAYS draft 3 QBs even though we only roster 14 in my 10-team league. It's amazing how often this has come into play. Injuries and unexpected busts tend to make it necessary. If my top 2 guys prove dependable enough, this becomes easy cut fodder for any early season pickups I want to make. Palmer and Garrard didn't work out. Good thing Rodgers slipped and I greedily saw his value even though I originally was happy with my top 2 guys.
12) Check the waiver wire every week. The first 3 or 4 weeks are almost always crucial when the unexpected occurs. Even later in the year there will be guys on unglamorous teams that will magically appear who maybe haven't had any one great week but have somehow found the endzone say 5 times in 8 weeks.
13) (This should be higher). Watch the byes and especially keep an eye out for the teams with the attractive match-ups in the last 3 weeks! You'll thank yourself later.
14) Adapt. In some years I've had pretty much a solid 7 where I knew who was starting every single week. I tend to find this ideal as the less active lineup jockeying I do, the better the results seem to be

Sometimes that's not possible though and I know at least one season where I started 7 different QBs and still managed to reach the final game!
15) If things don't work out you can trade guys away for draft picks (or if you are ridiculously deep somehow) but NEVER trade away your future draft picks to get a guy for this year. I hate hampering my future efforts with the quick fix.
16) I won't give up an RB in their prime unless the offer is comically ridiculously in my favor (and it never is). RBs are a paradox. They have the shortest lifespan of any of the skill positions but this makes it of prime importance IMO to have them as my keepers. Super-stud years are to be highly prized and I really prefer riding that RB until his usefulness is truly gone. The key of course is to have the next stud be my pick as my RB3 or RB4 in a given draft and through either luck or pluck I've been able to do it time and again.
Wow that was, uh, long. Hope it helped some
-QG