As everyone else has said, keep active on the site -- it helps! I started my account a couple years ago, stuck with it for a few weeks, and then abandoned it because I got too busy -- I ended up gaining back what I lost, and much more. Now that I'm back, I think I'm doing better. I haven't lost much weight that I can tell yet, but just having to record the calories I'm taking in against the calories I'm burning through every day is keeping me on track and helping me create habits that I know will result in weight loss in the long run.
So again, definitely, stick to it! And good luck!