To start with you can use prelubed, precut shooting patches from your local sporting goods store to get used to loading and shooting your muzzle loader, but for best accuracy most folks eventually switch to ticking material. Now, I've seen two types of "ticking" at the fabric store, one of which is called pillow ticking. It's not 100% cotton and has a looser weave, not something you want to use to contain hot gas and grip a RB bullet. The other is called mattress ticking and has a nice tight weave made from 100% cotton. You will want to always lube your shooting patches with something, even spit will work if you're cutting the patches ahead of time but for consistency it pays to learn how to cut the patch at the muzzle. I lube my patches with a 10-1 mix of olive or mineral oil and beeswax and cut at the muzzle. Straight olive oil works too but I like to have something that won't drip and get messy, thus the beeswax. Pre-cut/lubed patches come in .010, .015 and .020 thichkness, and sometimes .018. I suggest that you start with .015 and see how that loads as well as how well it holds up after being shot. The mattress ticking that I buy measures out to about .018 thickness and I get good accuracy using a .530 ball in my .54 rifle. The same goes for my .50 using a .490 RB and the same material lubed with the beeswax/olive oil mix. I cut strips of the ticking material about 1 3/4 inches wide, or 4-5 stripes, then lays them in the warm lube, after which I lay them out flat on old rags and press another rag on top to blot up the excess. When totally cool I just roll them up and store in old pill bottles until needed. Then when shooting I pour my powder charge in, lat the strip of material on the muzzle and center a ball on top. Using the little nub on my short started I press the ball down even with the muzzle and grab the excess material around the ball, take my patch knife and cut straight across the muzzle. This should give me a perfectly round piece of patching around by ball. Then I use my short starter to get the PRB down the bore about 5 inches and seat it the rest of the way with my range rod. Cap or prime, aim and shoot.
Consistency is the key here, you want to keep things the same way shot after shot. Good luck and have fun!