What sorts of things should I avoid as a newbie to MTG?

[nursegodaime]

I am just getting into Magic the Gathering cards and I was wondering what sort of things are considered "typical newbie mistakes"? Is there anything that you have seen new players do that I could hopefully avoid? Anything that might have brought with them to a game that made them stand out as new?

I'm not necessarily talking about what not to buy or anything (unless it's revelant). Mostly just what not to do.