Beginner kit Ideas

Double action airbrushes control the air and the amount of paint released. The Badger 200 is a hybrid in that it basically is a single action brush, but has a knob on the end that controls the amount of paint released.

I would go with most any Tamiya kit. The early Sherman was a very easy kit to assemble and only one color. The German Panther kits are very nice also. the only drawbacks to the Tamiya kits are the price. Go online and save some money. Also the venerable Panzer II and T-34 kits which are older and not as accurate as today's newer kits, but they are affordable and build up easily enough. You can always get aftermarket parts to enhance them.

I was thinking about a sherman as well, what do you mean by early, M4, M4A1?

Tamiya's M4 Sherman #35190 is a great kit to start with. Tamiya's engineering is top notch.

Other kits to consider would be Tamiya's Panther G's and T-34's.

Probably best to avoid anything from Dragon for the first while, individual track links will drive you crazy if you're not too experienced.

Airbrush:

Single action. The button on top controls the amount of air. The amount of paint is controlled in some other method, if at all. The Badger 200 has a "nut" on the back of the handle you can turn out (counter clockwise) to increase or in to decrease the amount of paint and therefore how wide the spray pattern is. They are easier to use, but very dificult to adjust the pattern when using.

Double action: The button controls both the amount of air, by how far down the button is pressed, and the amount of paint, but how far back the button is pulled. It is easy to change the spray pattern, but learning to do it properly and therefore being able to get the results you want is more difficult.

The double action Aztec brushes can be adjusted to act like a single action brush, if desired. One advantage of this is you can set it up as a single action and, after getting used to it, change it to work as a double action.

Kits:

Tamiya's Tiger I kits are all supurb. I'd stay away from any of the open topped (i.e. the Marder III and Marder IIIM) kits to start. For your first kit or two, avoid the impulse to get after market (AM) detail kits for it. (Exception to this might be a metal barrel) Get a kit that looks interesting to you and just have fun building it up. It's hard to go wrong with the newer Tamiya kits, although, as mentioned, they are expensive. Once you get a kit, jump on here and ask specific questions and the members will help with tips and techniques.

The main thing is to have fun!

ManiK_Impressive,
If you are thinking of a Sherman, may I suggest the Tamiya M4A3 kit #35122. It's an older kit but I think makes a nice kit and you can still find them rather cheaply (they are out of production).
Regards,
Joe