The most important tip that I can think of for weight loss? Track everything you eat. When you start making a list of everything you eat on a daily basis and say to yourself, "Man, I eat a lot of damn food," you'd be surprised how much less you eat.
I've lost about 15 pounds over the last three months, and a lot of it has to do with my use of
The Daily Plate, which is on the Livestrong network. It helps you with safe, sustainable weight loss (1-2 pounds/week). You put in your weight and your lifestyle (sedentary, active, etc.), and your weight loss goal (maintain weight, lose one pound a week, lose two pounds a week. . .or if you're trying to gain weight, even), and it gives you a target calorie figure.
Me, for example. . .I was at 230 pounds when I started. My job (outside of going to the gym, which you can also track) is largely sedentary. The site told me that if I wanted to lose two pounds a week, I had to try to limit myself to right around 1,800 calories per day. That's net calories, subtracting the calories you burn working out from what you consume. The first time you punch in an extra value meal for lunch from McDonald's. . .1,350 calories for my personal fave from there. . .and you see the little thing that says "you have 400 calories remaining for today," you feel kind of crappy and avoid doing that too much. Of course, if you want to hit the gym for an hour and burn a bunch of calories, you can punch that in and watch that figure go back up.
Also, as somebody else said, don't underestimate the importance of cardio. Doesn't necessarily mean going out and running a few miles or whatever. . .I hate running, myself, but it's a necessary evil in my line of work. . .but the elliptical trainer is your friend, especially if you have bad knees or ankles or something. Even 30 minutes a day is good, and it doesn't necessarily have to be super intense, either.