well i find both really helpful to do working drawings and illustrations on models but both are basically done the same way....
for both of them i create a template to draw clothes around/onto... these are easy to do but it did take me a while to perfect them because i tried my best to make them proportinal to a womans body.
but once you have made your template the hard part is over because after that all you have to do is put it under the paper your drawing on and use it as a guide.
i've included pictures but some arent very visible since i havent got around to finelining them yet
if they are too hard to see tell me and i'll try and rescan them
there are also some useful threads for inspiration
http://www.thefashionspot.com/forums...ons-19231.html
http://www.thefashionspot.com/forums...tch-29274.html
and im sure there was a thread on templates somewhere