My approach is different from most here. I don't mind tracking 30 stocks as they are all in one place and it takes 15 seconds to scan fidelity's page to "track" them. With Amazon , Google, CYDY, and cash taking up 50% of my portfolio, the positions in the the other 27 stocks are small. Lately I've been investing in a sector that seems like a value. For instance I have MRO, XOM, WTI, PEO, and Chevron. If one moves up more than then rest in a day for some reason, I'll sell some shares and move it into one of the others. If one is down 5% and the others aren't, I'll deploy some cash and acquire some.
II know I son't want DFS to be more than 5% of my portfolio. I might enter at a 1% stake. If it goes down, I'll add another 1.5%, and then another 2% if it drops lower. From there I'll usually stop, although in the case of Blooming last time, I bought more and ended up at 10% of my portfolio. For me, this was an uncomfortably large position to hold. If the case of DFS, when I'm ready to invest, I'll look to see if I like another stock like SYF and spread that initial buy between the two.
If it's a stock like several of the biotech I had where I'll never own more than a 1% position, I'll sell half after a 50% gain, a quarter after 100%, and then the rest after 200% if it ever gets there. If it's a normal stock like WFC where I'm comfortable with a 5% position, I'll start taking profits as early as 20%. If I'm say trading, I'll exit with only only a 10% gain.
A lot of this strategy is based on the belief that guys around here like Todem are pretty damn smart and this market is going to have a pull back. I don't mind taking profits since I want to maintain my cash position and the only way to do that if you are buying stocks is to always be selling some too. When the time comes and I fell like I want to to be 100% invested in stocks this will change where I'll hold my stocks for much longer before selling.