I am vegetarian; haven't eaten meat or fish for over 30 years and never will. My reasons are ethical and physiological. (Let's not get into one of those arguments like we do over religion and Politics, eh?)
Apart from that:
Yes
As much "clean" food as possible I.e. unadulterated with additives, preservatives, and salt and sugar that does not occur naturally in these foods. For example, bread should, ideally, contain only flour, yeast and water. (Look at the side of a pack of sliced bread)
Dark green vegetables, pulses, and almonds or walnuts for protein and calcium
No
Fried foods
High fat foods, especially saturated fats
This is me at my very, very best! While I have never fallen off the vegetarian wagon, I frequently topple off any other. Particularly when faced with chips..