I've been on morphine 30 mg tablets, what's the best way to taper off of morphine?

Take less: You could either cut the tablets if they are not extended release or use a smaller dosage formulation. You probably could reduce by about 10% ever three or four days without too much trouble. Some feel that you could reduce by 25% in that same period. Depends on your motivation and how much withdrawal symptoms you can tolerate. There are meds that will reduce those symptoms significantly.