I think of myself as an "advanced newbie", so I've been there not long ago, looking for the perfect kit to start with.
I'm 100% with Rob on this one : while you don't have to pay over 100$ for your first kit, please don't go on the el cheapo route. Sometimes shelling just a few dollars more will get you a nice and easy kit to begin with, and not something that you will want to throw in the trash after a few minutes. AND for plastic's sake, get a vehicle that YOU like, because, trust me on this one, you will loose interest and won't finish it.
One more thing : I would suggest to try a 1/35 scale kit first, for a very simple reason : size ! Very easy to assemble, paint and put nice details on it.
1/72 scale vehicles are cool (believe me, I've done my share in this scale) but many parts are so tiny that you need microscope instead of your eyes !
Like most others said, an original Tamiya tank is a great choice as your first kit.
Enjoy !