1) DON'T diet. diets NEVER work, and that's because it's a short term solution for a long term problem. you go on a diet, then you go off it. the good thing is that you lose weight on a diet. the bad thing is you gain it all back when you go off the diet. so. don't diet!
2) just eat sensible! (I maintain myself in the fitness industry, so I'm speaking only from what I know works & I've had 2 babies/c-sections myself!) You don't have to starve- but you DO have to make good choices.
3) Guidelines: (a) if you have to drive-thru to get it, don't eat it or drink it. (b) if the smell lingers in your car for hours, you probably shouldn't put it in your body either (who knows how it's lingering in your stomach!) (c) if you need to soak it with cheese, gravy, dressing, mayo or salt in order to make it taste good- then skip it altogether it isn't worth it! (d) reduce your carbs by switching to brown rice, corn tortillas and spelt bread (e) don't drink your calories!!! you don't need juice or soda and stick to coffee black with fat free creamer (if needed). (f) frozen entrees or 'quick' meals for the microwave are terribly processed and if there are words on the ingredients list that are difficult to pronounce; its LIKELY it's difficult for your liver to process as well. (and your liver plays a part in weight loss too!)
4) If you need DVDs for the home to tighten your abs, good starting points are PILATES. but you really need to mix in some cardio so if you can get outside for power walks or add in some running or swimming that would be BEST for your core. Try Pilates and 30 Day Shred. Both are great workouts.