Also look over in the Virginia Forum...the current post about leader material and knots. Some discussion going on there now about this very thing. Not sure what knot your trying to tie or what for but that post should solve it.
Just some tips : always moisten the knot before you tie it. And if you make a mistake while tieing it or it doesn't look right, re-tie...otherwise you'll pay for it later. Also, on heavier mono, if the knot requires turns, use less turns than you normally would with lightweight mono. And a dab of Pliobond helps it last longer. Be careful if you tie different materials together (ie, mono to flouro)...Fluoro will cut write through mono if under stress.
Tight lines....are due to strong knots!