one of my leaks-start strong...fold to big river bet

This happens to me too often. Any suggestions?

Pre-flop I have a very strong hand. Say AK. I bet 3x or 4x and get 1 caller. I'm out of position. Flop comes and I don't connect. I C bet (half pot) and get called. Turn comes and I don't connect. Here I may just check or bet again but the bet will be weaker (cause now I'm afraid I'm beat). River comes and I check and my opponent makes a pot size bet. I fold.

Thoughts? Thanks folks.

You do need to know a bit about the board though to make an assumption. Betting smaller on the turn makes you look weak and usually tells you opponent that you have nothing (usually). Then the check on the river confirms that so then your opponent can steal the pot. So if you are going to bluff, don't just give up on that one bet, because it doesn't always mean that your opponent has something.