Good advice above.
I'd just argue a little with Bodybuilder saying to buy in for more money. Yes, he is right, it is a better, more profitable game with deeper stacks. That's only true when you are good though!
While you learn it is fine to buy in short and play very tight. This will limit your wins but, when you aren't great at the game, it will mainly limit your losses. To be honest I still buy in short everytime I sit down and I've been playing for 7 years!
I do it because it prevents me losing a big stack in the first hour at the table when I might not know any of the players. Once I get to know how the game is playing I'll either add more chips or continue short stacked. While short stacked I'm spending 95% of my time watching the others playing pots, trying to read their hands, testing my reads vs any showdowns and getting a feel for any big table dynamics that are going on. 5% of the time I'm playing a strong hand as best I can with a short stack and limited reads.
When I add more chips, potentially up to 200bb in my game, I'm doing it to target particular players I have identified as weak or unbalanced in some way. I have a plan of how I'm going to take them on while defending myself against any tough players. I've always made that plan before I put a big stack on the table.
I prefer to view myself as cautious rather than cowardly but admit there are times I've missed big value when I flop monsters early in a session and felt more of a coward than usual