When playing a full ring game, sometimes it is best just to call in early positions, but when first in from mid-to-late position, it is a raising hand. When playing shorthanded, we should always raise suited connectors first in. This is to balance our raising hand distribution; it gives good deception value and allows us to steal the pot on the flop, even if we miss it completely.
If someone has raised before us, in most cases it is correct to call the raise, especially if we have position on the raiser. A good rule of thumb is that it is correct to call up to 10% of our stack preflop, since it is about that often we will hit two pair or better. Preflop, our cards are not worth much. It is after the flop that things can become interesting.
Our goal is to flop two pair, three of a kind or a strong draw. Suited connectors are especially good for stacking over pairs, but they are playable in most situations. If we miss the flop, we simply fold, unless we have raised preflop. If we are the preflop aggressor and the pot is heads-up to the flop, we should continuation bet even if we miss in order to give us a chance to pick up the pot. If we have called preflop, we only continue playing if we flop at least a good draw.The times we hit the flop hard our play depends entirely on the opponent, table image, table game play, stack size and position. To give a general advice for each situation that could arise would require an essay worthy of a Master's degree, so the only recommendation I really can give is to play the same way you usually play your good hands. The standard play, therefore, should be to play aggressive when hitting the flop hard