The most common mistakes people make when becoming vegetarians is not doing proper nutritional research. You're eliminating animal meat from your diet, which means you'll need to supplement protein, minerals, and amino acids.

On that note, I recommend (but do not require) a transition rather than a cold-turkey quit. I started by eliminating red meat, then poultry, then fish. I still eat meat, but I don't eat dairy. And that's my decision. Yours is your own to make!

Scott Young wrote a comprehensive guide of his own on the road to vegetarianism here. It's a great read, I highly recommend it.

Wikihow also offers a 3-step guide (it's a bit longer than that...you'll see) on the switch here. There's a hilarious video in the article, well worth the watch.

Those two articles have a common suggestion: tell your friends. This will eliminate potential awkwardness during dinner's out or at home. Believe it or not it will also strengthen your conviction to make the switch for good!

However...