Hotpants... or something simular to cover your stuff.
Suitable wig. wig is the most important bit, not much else people can judge you on... I bought a wig with a good looking fringe then bought extensions to make up the few inches of length it was missing.
white facepaint to correct eyebrow colour. natural eyebrows, appart from bright blonde, look stupid against the silver white wig.
red contact lenses.
black collar with brass fittings. make sure to measure your neck. use a little vasseline if your worried its going to rub.
black nail polish.
to style the wig i like to use. hairspray, spikeing glue, brush, scissors, hairdryer and a polystrine head.
Its a relatively cheap cosplay but needs to be assembled with care and attention to detail particualy on the wig. it wouldn't be hard to go from this into a suited version pluto cosplay.