I feel like the most important thing to remember in regards to betting is that the correct bet will always be an agreed upon price between the involved parties. With that said, you have to value your hand and your opponent's correctly in order to determine the correct pricing to see another card or show down. If you have A8 and flop a pair of aces, you probably shouldn't put a high enough value on your hand to call an all-in. That's AK price at worst, and even then (with TPTK), you don't want to be gii very often.
Always think in terms of bartering and you'll have a much better chance at getting the most value for your better hands and you'll also be able to avoid paying too much for your mid-range holdings. From there, you can find bluff spots and such, continuing to bet the same as you would otherwise and setting the price higher than your opponent can/should pay. Best advice I ever heard though is that bluffing
is overrated. It's much more important that you can get paid for your better hands by setting the right price and getting full value.