[Keitan]

Just to add: On the river it seems like you decide on your bet-size based on the strength of you hand. If that's not the case then never mind the rest of this post.

This is OK within a certain range like cbetting slightly less if you have a monster or when you think villain has hit the flop hard. But it's not a good idea when your bet-sizing can have a great influence on villain's decision. It also makes you more exploitable. For example, would you make the same 4$ river bet with quad Tens? If so, and you think villain knows this that's a different story, but I doubt that's the case.