Cosraints for Charicter rig

OK I sould know this already, but I dont and Ive been quitly trying to do with out it for to long so i’ll just suck it up and ask:
whats the proper way to use the copy location and or floor constaint to make a characters feet stickt the floor and or not go though it?

this is artwork section, use our support section for questions.

.b