Stealth + sniping based builds have never failed me personally. Usually a good pistol and long range rifle are all I really use unless I'm deliberately trying to build differently. Then it's all about always picking off enemies from as far away as possible, or as isolated from others as possible.

Been a while since I played but I think the main way to keep up with scaling is just to be diligent with choosing perks that give straight damage boosts to certain weapon classes and stick to those types. And with stealth builds, also building up whatever the main sneak perk that reduces detection is, until enemies finding you before you kill them stops being a problem that ever happens.