Hand 1: Bet more on the flop. To analyze the river, put together what you think his range is and how often he calls different sized bets. Then it's a simple EV calculation as to which bet size is best. Practice this in a few spots where you're not sure how to bet and you'll start to develop a feel for it.

Hand 2: Raise the flop. This deep you are just asking to lose a huge pot when the board pairs and you can't get away from your hand.

Hand 3: I think the flop bet size is about right, but you should bet more on the turn since there doesn't seem to be any part of his range that folds to a larger bet that doesn't fold to an $0.18 bet. As played, the river bet is fine.

Hand 4: Just calling preflop is a more profitable play in this spot (oop + omfg odds + it's not going to flop an overpair very often at all). As played, bet the flop harder, and possibly bet the turn harder. I'm seeing a common trend in a lot of these hands so far where you're betting too small - think about what hands fold to a larger bet size that you beat. If there aren't very many if any, then the larger bet size is almost always going to be better.

Hand 5: The flop bet is probably fine, but I would probably take a free card on the turn. As played, you've turned a hand with some decent showdown value into a bluff that isn't going to get any better hands to fold very often, which generally isn't a +EV thing to do.

Hand 6: Bet more on the turn. Think about this spot from your opponent's point of view. I bet he's thinking, "Oh shit he only bet around half the pot so now I'm getting better than 3:1 odds on my draw which makes this massively +EV."