[King Yao]

Are both players calling you pre-Flop, Flop and Turn? Or is it just one?

Assuming there is only one opponent by the River, it depends on the player:

1. Check/call against players that will bet for value - these are players that will bet with any pair (4s, 6s, 7s) if you check to them on the River. The reason I wouldn't bet into them is that if they have a strong enough hand that they'd call with, then they'd bet with those hands if you check to them. So in the case that they would call your bet, you don't lose a bet because they will bet if you check. But if he has a straight or a 5, you save yourself from putting in two bets (or getting bluffed out if you intend to check/fold) if you bet. You also get the value of possibly inducing a bluff from a busted flush draw or just Ace-high that may not have called a River bet based on the scary board. So against value-bettors, check with the intention of calling.

2. Against those that you can't expect to value bet as often, bet. If you check, you can't count on them betting for you with a hand like a pair of 4s. But if you bet, they will call with a pair of 4s. So you lose a bet if you check against these players. You can also divide players in this category into 2 sub-categories: players you are sure you should fold if they raise you; and players you would still call if they raise given the pot odds.

In general, I think a typical 3-handed 30/60 online player will be more like player 1 than player 2. So without knowing any of the players, if it was against only one opponent, I would check/call on the River.