Any tips for eating a healthy vegetarian diet as a broke high school student living in a non-vegetarian home?

Basically, I'm not really sure how to go about being a vegetarian in a household where the groceries are bought for a meat eating family. I live in a very traditional Southern family in Texas and meat and steak are kind of a big deal. It's quite abnormal for people to be vegetarians and most of my friends who are vegetarians eat french fries all the time. Mainly, I'm doing this because I don't want to support factory farming and for health benefits, therefore I'd like to eat less processed foods, and maybe even cut out milk and cheese.

So please if you have any tips, please help a fellow redditor.

TL;DR: read the title.