Well the first thing that I have to say about painting tanks is that it is completely different from painting miniatures. The reason for that is that there are very large flat spaces involved. This means that colors have to flow a lot smoother. The techniques for painting tanks really difffer if you are going to paint a camoflauged tank or not.
When painting camouflaged tanks the technique that I suggest you use is the drybrush technique. First just paint the colors you want for your camouflage in diagnol stripes. Then apply a heavy drybrush of the corresponding color with its highlight. Just remember to leave a dark line on either side of each stripe. keep repeating the process making the drybrushings lighter each time with a lighter highlight untill you are pleased with the results. The rest is exactly like a regular miniature.
Painting flat tanks schemes actually takes a lot longer to paint. The only thing you have to do is paint it as you would a minature except that you have to really water down your paints. This means that they will take a lot longer to dry. Just be patient. Other wise just paint everything else the same as you would a norm mini..