Clove Hitch and Half Hitch.
These knots are two of the easiest to tie and work well when securing a rope to a bedpost. They can cut off circulation when enough pressure is applied, so they should not be used for suspension, to tie around the body, or with wrist and ankle cuffs.
Clove Hitch Using Loops
Clove Hitch Tied with Rope End
Clove Hitch Using Half Hitches