This is a really broad question so I'm going to give a broad answer. In general, HA is better for this kind of thing.
Think about what you want to accomplish and adjust it based on any reads you have. What range do you have your opponent on and what do you want them to do? Based off of this, what bet size best accomplishes your goal?
For example, if you are against a calling station and you are betting for value, bet somewhat larger as few will notice and fewer will adjust. If you are betting for value with a monster against a bluffy raise/fold type player, bet smaller to induce. If you are betting for value against someone who you think is really weak, bet smaller on the river to give them better odds
Overbetting is often beneficial in situations where you have the nuts on scary river boards. If you hold a boat on a 4 flush board, overbetting would be appropriate against fish. If you hold AQ on a KJT9x board, there is a strong likelihood you get a call from a Qx.
Small river bluffs work if you have a bricked draw vs draw read where you beat nothing. This generally requires some reads and is best done when balancing your range against small river value bets when you think your opponent is very weak.
As a couple rules of thumb, if you do at least some bet size balancing, you can generally get away with betting larger for value and smaller for bluffs. Also big pots should be for big hands and small pots for small hands.