There are too many potential mistakes that will cause you to lose ev for me to list here. Here's an incomplete list:
missing preflop value by folding profitable hands.
losing preflop ev by raising unprofitable hands.
missing flop value by checking too many strong hands.
losing flop ev by betting too many hands.
etc.
A lot of players have improved their games by using tracking software, but I'm not one of them. I've never used trackers. This is why I think it's more important in the poker environment of today to just go ahead and learn what good players consider good poker; this doesn't mean to imply that you should copy good players. This means you should copy the thought process that they use when determining the best play.
First thing? Nail down your preflop ranges. I don't mean using a chart when you play and I don't mean having a rough idea of what your range should be. I mean have that **** memorized for typical game conditions. Me? I used flash cards to memorize standard ranges and I did lots of work with an equity calculator. Now I know where the margins are and when to deviate from my default strategy.
Second thing? Study pot odds and what the math represents: it's all about the size of your investment relative to the pot and how much you can win or lose later in the hand. Contrast these situations:
a) you have a clear bluffcatcher and your opponent is all in, you're closing the action getting ~3:2. You should almost immediately know that you're making a 40% pot investment, which means you need to win the pot 40% of the time or more to call profitably. If your hand doesn't have 40% equity, then it's junk and you should fold.
b) you have a clear bluffcatcher and your opponent has bet the flop after raising on the button. He bet 1/2 pot and has about 75 big blinds behind, which you cover. If you call, you're making a 25% pot investment, which means you need to win back 25% of the pot on average in order to show a long term profit.
The most important, and the most strategy influencing factor here should be the possibility of losing future bets in the second scenario. This results in very different calling ranges in each of the above situations. In the first situation, your bluffcatchers are benefiting from the lack of reverse implied odds, but your draws are suffering from a lack of implied odds. In the second scenario, even though the investment is smaller bluffcatchers are in a much tougher spot, while draws are benefiting from the big implied odds.
Then I think a brief history of poker theory will help to get you up to speed:
https://forumserver.twoplustwo.com/1...08/?highlight=
After that you'll probably have some questions and you'll be in a better position to identify leaks on your own.
good luck.