To the best of my knowledge, this represents the cutting edge of what we know.
#1: The best summary article I've come across
is Christian Finn's. He has tons of great advice on his site, and we're both fans of Tom Venuto's BFFM book.
The most important thing to take away from Finn's article is that weight lifting + cardio is the best combination for burning visceral fat and subcutaneous belly fat. Check those numbers out! Three times more fat lost than cardio alone.
#2: Don't forget posture! You can have 12% body fat and still look like you have a belly. I've been there.
Ironically, sucking in your belly is not just something you do to temporarily look good -- it exercises the transverse abdominus muscles that lead to better posture and eventually a slimmer looking waist. So read up on
the Stomach Vacuum and hop to it! Don't neglect your crunches or your lower back exercises either.
Bigger ab muscles, less fat to cover them, and good posture = amazing abs.
#3: Not diet, but good lifelong eating habits. Here again, BFFM has the best laid plans for you. Eat 5-6 meals a day of roughly 350-400 calories apiece, drink plenty of water, shift carbs towards the mornings and protein towards the evenings, etc.
Remember, this is not about eating less. It's about eating better.
#4: But what about calorie deficit? Don't I need that to burn fat?
Yes, absolutely. But there are several ways to achieve a deficit: eat fewer calories, or exercise more. Exercising more is your key.
A nice side effect of eating better is that you'll also choose food with fewer calories, more nutrients, and which are just as filling -- but set your eyes on increasing your daily activity and exercise and don't worry too much about calorie cutting.
#5: Okay, fine. So what exercises do I do? What do I eat?
These topics are covered extensively in other Traineo posts.
Any decent 3x or more a week weight lifting plan coupled with a moderate to intense 30+ minute 3x a week or more cardio plan will work.
BFFM has great advice on what to eat and what not to eat, but you can find similarly great advice from vegetarian or near-vegetarian proponents. As usual, you can still make great progress without following the new eating plans to the letter, but the closer you are the better you'll do (I'm by no means a vegetarian, for example.)
Note: I originally put this article together for myself, to outline where I wanted to go next in my own quest to get fit.