Whether you play in no deposit poker freerolls or in money games you ought not to play in games that are too tough for you. Remember your my bankroll is what it is and even if you it were more it will not.
You might be forced and tempted to move up and win money faster because you are confident in your game, but cool, moving up can put your hard earned bankroll at the whims of variance. Do not play games in temptation. Growth comes automatically when you are playing things right.
There are more than normal chances that you have an ongoing quest to mark the weaker players; however you need to watch the ones that start with poor hands, and also you need to watch the ones that chase, that bet draws, that refuse to fold or those that play too tight. These are the people you can make money from.
This is true in no deposit poker freerolls and real money games, learn to exploit them. If you think you need to leave them at mercy remember no one is going to leave you at mercy. So, commit yourself to squeezing money out of everyone coming your way.