I often hear this question in two context: 1)a non-vegan being snarky about my unfamiliar looking meal 2) a new vegan befuddled by what rolls off my tongue as a somewhat experienced veg-head.
I think the biggest mistake you can make in any new endeavor is immediately starting at level 3. Think of a brand new skier hopping on the slopes and immediately going for one marked with a jack rabbit. Stupid and disheartening when said skier is run over or simply out skiied.
Food is the same way. If you are incorporating new vegetable based foods in your diet why not try decreasing meat intake slowly and simply eating more healthful plant based foods (i.e. Have a chicken salad for lunch instead of a burger. Have fish tacos for dinner instead of a steak.). Since meat is addictive it requires weaning for some.
Quitting meat cold turkey (pardon the pun) and running to the store to buy tempeh and seiten is bold, but can be disheartening (i.e.gross) if you dont know how to prepare these items.
To start eating more veg-based meals read some veg cookbooks and see what looks/sounds good to you. If you like a particular ethnicities foods start there. Italian food your weakness? Try a yummy plate of spaghetti marinara or a veg lasagna (think Regular lasagna just dont add meat or sub it out for Veggie Crumbles meat replacement or Tofurkey Italian Sausage).
A really easy way to get used to veg food is to eat in restaurants that offer it on the menu. Last night I went to P.F. Changs. All of their menu items marked vegetarian are vegetarian. Who would have thought! Vegetable based and delicious I might add. I ate there last night and had the Buddha's feast with a pot of tropical green tea. It was just what I needed to calm down, relax and refuel. Many chain restaurants offer veg options. Check the menu online and it you still arent sure feel free to call ahead and ask.