Don’t bet if only a better hand will call.

I sometimes still make this mistake. Let’s say I’m in the BB with J5o and there are three other players in the hand with a board of the following.

Kh 6s 9d 10d

So far it’s been checked around and a 5 comes on the river for a final board of 

Kh 6s 9d 10d 5s

No one seems interested and I just hit the 5, so I bet. Well, who’s gonna call? Only someone with a K, 6, 9 or 10 and even a pocket pair is possible. It’s best just to check and hope your 5 holds up. If someone bets, fold because you know your beat.