NL - unimproved middling overpairs (best line in theory)

[NANONUTS]

Check raise is by far the best option. If you flat call the villain is not gonna put anymore money in the pot unless he improves or a scare card comes that he can use to take you off your hand. He also has the option of firing a second barrel to represent an overpair and can take you off the hand this way too. If you cr and he calls 90% of the time you are beat and you are out cheap.
I mix it up between leading and check raising in these kind of spots. If the villain flat calls a small leading bet on the flop he very likely has overcards and 80% of the time he'll fold to a decent size follow-up bet on the turn.
As jack_plyr says it's all about the villains preflop raising frequency. If he's raising alot remember he has nothing most of the time so don't let yourself be pushed around.