You mean your neck or the fixing point?
For your neck - slipknot with 3 coils for partial or full hanging, hangmans knot with 7 coils for drop hanging
For fixture, bowline or two loops and two hitches (I think thats how it was called), but I prefer to make a slipknot and put the other end of the rope through it and tighten it (google pictures for 'how to tie rope to a tree')