There are three "edges" you can have playing poker - having the best cards, having the best position, and being the most skilled. While you're learning, focus on playing the best cards in the best position - in other words, if you're in early position (utg or in the blinds, for example) stick to premium hands like TT+, AK, maybe AQs, and in later position (btn, for example) you can play more hands (77+, KQ, QJ, JT, etc.) since you'll be able to see what others are doing before you.
Once you start getting the hang of things and read/study/absorb as dj11 suggests, you'll be able to develop a skill edge that will allow you to spend less time worrying about whether your hand is good enough to play or not, and more time thinking about how to exploit the other players at the table.