I am right there with you...over the years I have consistently taken profits too early and watched the move continue without me. I am currently working on a system right now that will keep me in the trade by taking the emotion out of it. I think that is the way to go, at least for me.
I have always had great entry points, but end up getting out way too soon. I can't help but ring the register. The emotions sometimes take over and I bail. Then sometimes I end up going the other way against my original position and ending up getting run over! I know it's not very smart, but it is a bad habit that is very hard for me to break. I have been a profitable trader for the last 10 years and my style keeps me out of trouble with very little drawdowns, but I know that I "shoulda, woulda, coulda" made a lot more.
That is why I think that having some sort of exit strategy is key to success for a trader (duh!). Whether you use a price target, bar reversal, moving average, indicator cross, etc...it doesn't really matter! Just use something! Experiment and find something that works for you and start following it. Trust it. You will find your average winner will get bigger.
Bad trades and losing trades will happen. You can't avoid them. So stop avoiding the good trades! We have to stop fearing the loss of our gains and see how far the trade will take us. We must let our rules guide us instead of our emotions.
Hang in there!