+1 on priming & +1 for spray cans for easy priming.

I use matt black undercoat from Army Painter and love it.  I actually find it better than the Tamiya stuff which is saying something.  They also do other colours for their primers. 

http://shop.thearmypainter.com/products.php?ProductGroupId=2

Warm before use, shake well and a quick light coat to cover.  It's actually pretty hard to mess up.

& for plastic preperation just wipe the model down with some metho and let dry before painting.