hey buddies,here it is:
1.wipe the tank all over with the mixture of Zippo oil and Oil paint(Coal black color &Ocher color),and for the "mixture",sth like dirty pasty oil(I really don't know how to describe), and for the ratio,the more rusty,themore Ocher color in it. And then wait for several minutes,5-10 minutes,maybe.
2.use a cotton cloth(tiny knot better) to wash the "mixture" very very lightly so that you will leave some trace like rust,muddy,or sth dirty for tanks.
3.after the wash,then a quite long time,you can put your tank anywhere to make the tank dry as quickly as possible, it will last maybe 8-10 days,or you can use a hair drier to make it a shorter time.
4.then after the dried wash,use Tamiya Metal paint(or 8B pencil) to make the paint peeling off effect(my poor English,is there any word for this??)
5.almost finished,last step use clear lacquerto protect thecoating or your tank.

That is the simple step for this,and my methord for 1 16 tanks.
Just have a try, to make your tanks more realistic!!!!!!</p>