These guidlines will help you to decide when and how much to bet.
Very important: Every bet you make should serve a purpose!
I.e. to get your opponent to fold, call or raise
Betting is like telling a story. It has to make sense otherwise your opponents wont follow you.
Matching the pot size
Putting more money in the pot than the person before you.
Giving up your hand when the action reaches you.
But dont forget to watch the players who still play after you folded. You can pick up valuable information about they play. Know your enemy!
You have as much money in the pot and dont want to raise or fold.
If you play in a real casino not online, always announce the size of your bet. The announcement is binding and if you accidently put more or less chips in the pot than you wanted, you can adjust them.