Isopropyl and Sea Salt - Works everytime.
The easiest way to clean your pipe is with 91% pure isopropyl alcohol and sea salt. Simply pour in about 2 tsp of sea salt and submerge the pipe in isopropyl.
Use a ziplock bag or small container with a lid to contain the smell.
Let it sit for a few hours or overnight if it's really dirty. Remove the pipe from the solution, plug the mouth and carb holes and shake the salt around inside. Then, rinse clean.
Vinegar and Baking Soda - Fizzy and fun.
Submerge the pipe in vinegar, add a dash of baking soda. Let sit in that solution for 3 hours. Remove, and rinse well. Clean the interior chamber with pipe cleaners if you have them.
This non-toxic cleaning solution works really well and you usually have the ingredients on hand anyway.
Boiling Water - Smells terrible.
Place the pipe in a small pot, cover with water and boil. Always use a pot with a lid, this method smells terrible. I left it in for about 30 minutes. Removed carefully, its very hot! Rinse well and use a pipe cleaner if you can.
Boiling water does remove a decent amount of resin, but not all of it. Definitely not the most efficient way to clean.
Nail Polish Remover - Super toxic, don't do it.
Place the pipe in a small glass container, fill with enough nail polish remover to submerge the pipe. Let sit for 3 hours.
This method completely obliterates resin. HOWEVER, it is extremely toxic and damaging to your lungs to inhale. If you must use nail polish remover, rinse thoroughly.
I don't recommend ever using nail polish on any smokeware, ever.