easiest way to make a camo pattern is go find some tree's with fallen leaves and branches. Spray the colour you want the branches or whatever to be ( brown? ). Then place the branches and leaves overtop the area's you want to have in (brown?) and proceed to spray pain in the colour that is most common to the area ( green? ).
That might give you a pattern more natural.
As for COD:MW Red-tiger-stripe, paint black, cut stencil out of paper to fit your pattern, then proceed to spray on red for the red stripes, or vice versa.
edit: haha never answered the question on camo.... Uuhh sure - it looks cool i guess, but you need to play the part. If you intend to do it, gotta do everything. ( Camo gun, but your bright red/pink? Lol )