1.- Eat 5-6 times a day in reduced quantity
2.- Drink plenty of water
3.- Anaerobic training is important (i.e. strenght training) because it helps to build muscle tissue, and the more muscle you have, the higher your basal metabolism will be, and the more calories you will burn, even while sitting in front of the computer.
4.- Aerobic training (i.e. running, cycling, swimming) is important too, it helps burning fat faster, but don't do only aerobic training because you will burn both fat and muscle, and then, with less muscle you will burn calories slower. At leats 30 minuts of aerobic training per session.
5.- Protein is important to fuel the muscles (meat, egg whites, tuna...)
6.- Avoid fat, specially animal fat
7.- Avoid processed hydrocarbs (pastries, cakes), candies, chocolates
8.- Eat lots of fruits and vegetables.
You should look into the history of the lipid hypothesis. You might be more hesitant to make such strong statements.
Check out "Good Calories, Bad Calories" by Gary Taubes. The title is pretty bad but the research is epic.
It's been discussed many times here on HN:
http://searchyc.com/submissions/hacker%2527s+diet?sort=by_da...
Personally I used it to lose about 30 pounds over the course of about 6 months, and I've mostly kept it off. I'm going back onto it to lose about 10 pounds that have crept back on.
Related note: http://alwyncosgrove.com/2010/01/hierarchy-of-fat-loss/ is probably the best summary of what to do on the exercise side..
Good Calories,Bad Calories is a book that gets recommended around here quite a bit. I haven't read it myself. Sugar Busters is an interesting read, as it actually covers a bit of the science used in coming up with their program. Flaws in their method have been discussed ad nauseum, but the biology behind it seems sound.
There is also a wiki covering some of the material with videos: http://startingstrength.wikia.com/wiki/Starting_Strength_Wik...