A hand starts before the flop but the big money moves in the pot after the flop. But that does not mean that you can ignore a good strategy before the flop. There, you set the right tracks to win the big pots. If your preflop play sucks there’s no way you can win a lot even though you’re playing well after the flop. Playing before the flop is not that difficult but you have to understand what it is about: It’s about setting up your hand for the play after the flop.

Playing tight
This is the major principle. You have to play tight before the flop. You have to select the right hands. You shall not play every hand or hands that don’t have any potential. Let’s take a look at some hands that are good and which are not:

AK - a monster hand with a lot of potential. Most of the time you flop top pair and can bet for value.
A5 - although it’s an ace it’s a weak hand. The 5 is your problem and can only bring you in trouble.
K9 - looks good but is an awful hand. A king is way weaker than an ace and the 9 has no potential whatsoever
88 - that’s a good hand because it’s already one pair and if you flop another 8 you’re the king
97 - no potential for top pair hands. Only some chances to make a straight. But those are tiny so don’t waste your time with this hand
KQ - not a great hand but also not a bad hand. You can play it and you hope for top pair or some straight draws

We don’t need to talk about worse hands. It’s obvious that hands like 42, T4, J3, 85 and stuff like that is not playable.

How to play
If you found a hand you want to play, you should play it aggressively. Don’t just call before the flop - raise! Sure, if you already have two players in front of you that made a raise you can’t raise with a hand like 88. But if nobody showed strength you should raise such a hand.
If you raise you should raise four times the amount of the big blind. If you’re playing a game with 0,02/0,04 in blinds you raise to 0,16. And for every player that entered the pot in front of you, add one more big blind to those four big blinds. So raise more when other players already entered the pot.