What size should I make a hole that I am going to tap / what size hole should I make that will be clearance for something with threads?

When we tap, we want to drill a hole that is slightly larger than the thread’s minor diameter. Clearance holes should be slightly larger than the thread’s major diameter, to allow free movement between the thread and the hole.

A tap/drill chart is a handy tool for looking up the recommended drill sizes for these holes. More details here.