The most basic question in poker is "Should I fold, check, call or bet?" The answer is quite simple:
You should always make the highest EV play!
Expected Value (EV) is the average amount of money we expect to win as a result of an action. We must consider not only the immediate result of our action, but how it cascades during the remainder of the hand.
We can imagine an EVcheck, EVfold, EVcall, EVbet $8 and so forth.