You have to ask yourself why you want to become a vegetarian. If its it health reasons, eating animal protein in proportion is healthy. Make sure you eat well rounded meals that include protein fats fiber fruits and vegetables. Nuts and nut butters are great. Be careful of what you eat to fill you up. It can't be high in sugar.
I eat alot of beans, salads filled with fruits and veggies. I stay away from breads and pasta. I still eat dairy products and some seafood.