My biggest tip .... don't do it yourself!! Unless you're an experienced waxer, it's a bad idea. I'm a beauty therapist and I don't do my own bikini line.
If you must though, I'd say cloth strips, never tried muslin but wouldn't have thought it's be strong enough to wax with?? not sure - maybe someone else has more experience with that? I can't get on with paper strips either.
Apply the wax in the direction of hair growth and pull the strip off in the opposite direction. This is one of the reasons it's better to have someone else do it, as they can see if the hair is growing in different directions!
Also make sure that you press the strip down really well onto the wax and tear off as quickly as you can. Don't be timid either, it hurts more if you try to be too gentle!!
Good luck.