[COD]Any class building advice to follow/mistakes to avoid that you guys can give newer players?

What I can give is: 1. Test out a weapon's iron sights, don't use a scope on a gun if its iron sights are good OR it needs different range, i.e. putting an ACOG on a sniper. 2. Use suppressors and Ghost together, or else there isn't a point. 3. Laser Sight is a godsend on almost all SMGs and non-slug shotguns. 4. Put it in a class if you use it. if you never use tacticals, those points can go elsewhere. 5. The rarest variant isn't always the best.