Losing is part of the game, the object (obviously) is to win more than you lose. A few simple tips:
1) Never fall in love with a stock. Use it like a cheap prostitute, buy it, use it, discard it.

2) Do your DD! Never trust what others are saying, do the research yourself by looking at technicals and fundamentals. NEVER jump on the "bandwagon".
3) TAKE YOUR PROFIT. Don't keep hanging in there with a stock. If it looks to be levelling out, it probably is, sell and take your profit. Don't cry if it goes higher, you made money, be happy.
4) TAKE YOUR LOSSES. Set a number to the most you're willing to lose and SELL when it gets down there. Don't keep thinking the stock will go back up, it might and it might not. More often, it keeps going down and you lose your buttocks.
In my experience noobs lose money because they don't follow these rules. They see a forum post or hear about a stock and blindly buy it. Buy on logic and not emotion. Trust only yourself and if you can't trust yourself, you shouldn't be playing the market. It's fine to read what others say, but as the great Ronald Reagan said "TRUST BUT VERIFY".