I am quite intrigued by eating according to your blood type. It makes perfect sense to me, knowing the foods that i have a sensitivity to. Also food combining has some good advice too.
Best thing is to keep a food journal for at least a couple of weeks. write down everything you eat/drink, when you eat, where you eat, how you eat and how you feel before/afterwards. It will tell you lots about your habits so that you have a good knowledge and can pick the right plan for your lifestyle/food preferences
there is no point in setting yourself up to fail by just going with a fad diet that you will hate, not stick to making yourself feel worse) and make those around you suffer for too!
Also look at the American Medical Association website for a whole lot of stuff on healthy eating.