Nose butter - it's easiest to start by learning them on the knoll or knuckle, approach with moderate speed and set your self like you're going to do a spin off a jump (wide stance, knees bent, upper body and arms turned the opposite of your spin, ect.) then as you come up to the roll start spinning, bring your legs together and put as much weight as possible on your shins and lean over the tips of your skis. The harder you set and the faster you go the more you'll spin, it also helps to kinda pop off the tip when you get to 180 if you plan to continue spinning to 3, 5, ect, that way you're less likely to catch an edge.
Tail Butter - it's the exact same as a nose butter, but switch. Approach the knoll/knuckle/roll backwards with moderate speed looking over the should you most comfortably spin (obviously, you need to be able to ride switch pretty comfortably, and being able to do at least a switch 1 off of something small is pretty helpful) and have your legs staggered with leading side forward (so if you spin left, left foot forward). Then, just like with the nose butter, set you spin like above, and instead of getting your weight on your shins and over your tips, sit back slightly and pull your tips up (but try to keep your shins connected you the front of your boot - hard to explain, but if you can figure it out it will really help prevent shin bang), and spin off the knoll/knuckle/roll, but don't pop up until you get to 180, and then continue spinning as desired.
The key is having minimal contact with the snow on the butter point (tip or tail), and having nothing else contact anything so you don't catch an edge. Good luck.
~WAKIN' UP THE NEIGHBORHOOD TONIGHT!~