aye ive done an entire wing with halfords paints , and also done colourcoded arches on my old 205 gti , its actually fairly easy , the trick is preparation , keeping the spray area dust free , no humidity , and warmth , i used bin bags on the floor (in garage) after sweeping and damping down dust , also a small space heater , (it was winter at the time) , i also found leaving the cans in the airing cuboard overnight helps as it warms the paint and gives a finer spray. also let the panels heat up if its a cold day (left mine in garage with space heater for half a day. make sure you mask off areas ya dont wanna spray with newspaper and 'good' quality masking tape. and as said above prepare surface well with wet and dry. paint doesnt stick well to glossy surfaces so needs flatting. if your unsure , practice on the old small bumpers or somin similar.