If you mean you alwasy want to be shooting at brown, and never shoting at pink, then no. If you rememeber pink is CT, and brown is always T, then yes.
I installed new skins or models the first week of my CSS induction, it helped me tons with target aqusition. I still foobar once in a while, but thats usually just forgettting due to what gun is in my hand.
That thread has player models, skins, and whatever to help you better distinguish teams. Some are better then others. I'd stay away from the one that have REALLY good camo or look jsut like the surroundings, that will only make you suck in game. After all, this stuff is just client side and personal eye candy, nobody else on the sever can see it.
Oh course if you install bright blue and bright red models I'll personally come out to Indiana and smack you.