GOALS OF BIDDING:
It's tough to get anywhere meaningful unless you know where you want to go, so here's a look at what you need to make a game, slam, or grand slam (we will look more at these terms later, when we examine scoring).
To play a game in no trump (3NT) you want to have 25 HCP and no 8-card major fit with your partner.
To play a game in a major (4H or 4S), it's best to have 25 HCP and an 8-card or longer trump fit.
To play a game in a minor (5C or 5D), shoot for having 28 HCP and an 8-card or longer trump fit.
A slam (a contract at the six level) often requires 33 HCP and any appropriate fits. This ensures that you cannot be missing two aces.
A grand slam (a contract at the seven level) should not normally be attempted without 37 HCP and any appropriate fits. It is impossible to be missing an ace (and thus a quick trick to opponents) with 37 HCP.
If you can't meet these requirements, you may still have opportunity to make a game or slam, but you need hands with unusual suit distributions to make up the weight. Generally keep to what you can make.