ThomD said:Calories in < calories out. That's all there is too it.
Just like others have said this is spot on. Some of the traps people fall into are not realizing how many calories they take in.
Try to eat at home not out.
Just because something says low fat doesn't mean it's low calorie.
Little things like adding cheese, salad dressings, mayo, etc can really pack on the calories fast.
Soda's are packed with calories but so are fruit juices, you're better off drinking water and eating real fruit than drinking a couple glasses of fruit juice.
Just because you're eating organic, or natural, or whole grain, etc doesn't mean you'll lose weight. Yes foods like that are generally better for you and you should be eating them but to lose weight you still need to cut back on calories!
A workout that you enjoy doing is key, if you're dreading your workout it'll be hard to stick with, that's why for cardio i do trail running and mountain biking!