I take it you all saw the ARC trooper instructable?
https://www.instructables.com/id/more-on-the-expensive-side-ARC-trooper-cosplay/

this is from an enquiry on a just a plain Clone Trooper.
Well this is along the lines of the ARC trooper but some HUGE pieces are missed out.

this is basically for the helmet and the DC15A Battle Rifle.

Step 1: The Helmet

FOR BATTLE DAMAGE:
First, Start off by coating your Clone Helmet in Silver, avoid the back grill and teeth as they're important parts of the helmet's finish.
Then leave it about 2 weeks and with some fairy power spray, you're going to rub off the silver but do some areas with smaller effort so that you get a decent battle scratching on your helmet. it should end up like this.

FOR CLEAN WHITE:
First, you'll need some White insulation tape for the visor modification. then measure an inch from the plastic bottom of the pre-cut visor upwards then diagonally tape upwards. you should have a helmet like the bottom picture.

Step 2: The Costume.

This is the Clone base template that i use for any clone build as i can't fork out £1400 for full armour.
But you just don't touch this. leave it as it is. but get a turtleneck undershirt. and some white trainers.

Step 3: The Rifle

http://www.ebay.co.uk/itm/Star-Wars-Clone-Wars-Ultimate-Blaster-/230944707066?pt=UK_Clothes_Children_sFancyDress_RL&hash=item35c56091fa
the Blaster can be found here. all you essentially do is get some reference picture of the rifle, superglue the parts together and spray it gloss black.
or you can do a DC15s which you only need to spray black.

And that is your White Clone Done, hope you enjoyed.