Should you bet top pair for value on the river against one opponenet?

Say you have top pair top kicker, pair of aces with a king kicker and your at the river against a single opponent and the pot is a decent size, not huge, but not a tiny pot. There has been some betting on the flop or turn. There is a possible straight, but you are sure from his betting that he doesn't have the straight. He could have you beat if he has two pair or trips though. Should you try to check your one pair down, or bet for value? Often times I just check, but realize if I made a smallish half pot bet, he would have called with middle pair, or top pair with a weaker kicker. But sometimes, he checks first, and I bet after him, but he calls with bottom two pair to win the pot, and I would have saved a bet by checking it down.

Is there any good rule to follow about betting/checking one pair on the river?

Depends on your opponent

Depends on opponent and the Flop, your main fear is getting check raised althought it is unlikely he would of done this with 2 pairs or trips. Most of the time a half pot size bet or less should be good and i will normally do less if im confident i got the winning hand. I bet so small cos i want a call and any extra in a pot im gonna win is good.

But if you have been betting the river like this a lot with just top pair then he may have the check raise planned for you so do everything in moderation.

There is a sound technique here known as a 'block bet'. If you get to the river and you have marginal holdings (such as TPTK) and are unsure of your opponents strength as well as being out of position, then put in a bet for a quarter of the pot. This still signifies strength while if you just check here you are inviting a big return bet for half or more of the pot which can result in a real bad call or maybe making you fold the best hand. Because a quarter size potbet still signifies some strength it may even make your opponent fold a better hand on a scare board or give him enough doubt just to call you. You may still lose of course but at least you are knowing for a sensible price. Obviously you can fold to any re-raise but at least you know you are beat if this happens.

Don't forget the classic, "check to the busted draw so they can bluff" play !!