Since the Hollow Knight wiki does such a great job, I'll be focussing on charm builds, lore/theories, and fun things I find!
My charm build consists of the following: Sprintmaster, Dashmaster, Sharpshadow, and Quickslash. I'll then use the remaining three slots for quick focus, unbreakable strength, or some combination of weaversong, grubsong, nailmaster's glory, soul catcher, and unbreakable heart.
I enjoy playing glass canons and relying on dodging, so my builds (this one included) tend to be mobility-focussed. Sharp shadow in particular helps me deal damage with every dodge, and stay close to the ennemies so I can keep slashing (quickslash makes it extra fun here!)