Once I got a handle on playing a wider late position opening range, I used to make the mistake of assuming that I could call an open with that entire range. "A7s on the BT, right on, I can open this, let's play!" And then the CO would open before me and I'd be like, "Aww, I was ready to open, but I can still flat call because I have position, right?" This situation is a fold or a 3-bet, almost always a fold and at micro stakes definitely a fold unless the stacks or Villain tendencies tell you otherwise.
The one habit that took me longer to let go of was being unable to let go when I flopped 2-pair no matter how fugly the board ran out.
J9s and 2 limpers to me on the button. "Right on, I can open this!" So I do. Then even better, the flop is 92J-rb! "Sweet! Top 2-pair and no one can put me on it. I even have back door spades. It's just a matter of getting paid." It checks to me 3-way. "Gee, don't want anyone folding here. I'll bet small. Just a 1/4," (failing to price out draws).
Both Villains call. Turn is the 8di, busts my backdoor spades. "Grr, QT just came in. Bah, no one has that. And I'm not worried about those back door diamonds neither. Both Villains check to me. I should bet small again, but just in case someone has a T, better go half-pot." They both call. "Damn, what do these guys have? Oh well, so long as the river isn't a Q, a T or a dia ... it's the Q of diaomnds. Horror show card!"
Villain 1 bets 1/3rd. Villain 2 calls. "What the hell is going on here? 45 seconds ago I had a secret monster. You can't tell me that I still don't have a monster. Gah, they could just be
bluffing the diamonds. CALL!"
Then they show you the bad news. One of them a T and the other had diamonds.
I had to learn that he board texture changes your value. That monster is now a
bluff catcher. That took a while. It's even worse with broadway cards. I open KJo and get called by the SB heads-up. Flop KJ-rag. Sweet 2-pair. Turn is a T. SB check-raises me. Oh, look out! If SB is competent, he's likely defending out of position with 2 broadways. This is very very often AQ. Probably have to fold our monster.