I use epoxy to fill right to the top of the hole. If the hole goes through, I put a piece of painters tape on the bottom to keep the epoxy from dripping out.

Then I drill the proper starter hole and put the post/screw back in.

Toothpicks and wood glue work just fine, just a matter of preference.

I should add, I use West Systems epoxy, and have several different hardeners depending on desired pot life. I mix by weight, and use TAP plastics resin dyes if I ever need to. Micro balloons as an additive if weight is a concern.

Why not just fill the hole with epoxy instead of sticking a toothpick or q-tip stick in it?

I agree that it's a little more work, but I disagree that it's not as good of a repair. I think it's actually a way better repair.