Steps in loading ANY shoulder-fired muzzleloading weapon:

1. Put the lock to half-cock.
2. Pour a measured amount of powder down the barrel (this can be froma pre-made cartridge).
3. Bounce the butt of the weapon on the ground or whack it about the lock with your hand to settle the powder.
4. Place a lubricated patch on the muzzle (the lube can be tallow, special concoctions, bacon grease, spit...there are a million recipes for lubes).
5. Place a ball on the patch and "start" it down the barrel (with a short-starter, a wooden mallet, the ramrod...). (NOTE: You can also use the cartridge paper as a patch. The patch is used to seal the gases behind the ball and thereby provide more accuracy and power.)
6. Using the ramrod, drive the ball down to the powder -- preferably with one motion. GENTLY tap the ball to insure it's well seated.

6A. For percussion locks: place a percussion cap on the nipple of the lock, and gently gently lower the cock from half-cock to the nipple. If you're going to shoot right away, pull the cock to full cock, aim, and fire -- and repeat the steps above.

6B. For flintlock: with the lock still at half-cock, raise the frizzen and place a few grains of priming powder (modern 4F) in the pan and close the frizzen. Either lower the lock and flint to the uncocked position, or pull the lock back and, after assuring yourself that the flint is well and truly in place, aim and fire. If you must, you can use a few grains of powder from the cartridge or any powder in the pan -- priming powder just works better.

7. After firing, run a ramrod and patch down the bore. This will help put out any remaining powder that might be smoldering and prevent you from getting a nasty surprise when you reload (see step 1, above).

Now, consider those oldtimers who could reload a flintlock while at a dead run...or on horseback...or on the deck of a rolling ship...or when prone...or while being shot at...or while in a tree...or....

This is from my own experience as someone who shoots muzzleloaders. Loading a single-shot percussion or flint pistol is like loading a rifle. Loading a revolver...well, you have to seat balls in the chambers that are slightly (0.451" for a .44 caliber) oversize, grease the ends of the chambers to prevent chainfire, and try to insure that your caps don't fly off the nipples with your first shot. Caps flying off are embarassing on a range and could be fatal in combat; chainfire -- when all of the chambers in the cylinder fire more or less at once -- can be fatal anywhere, but it IS impressive as all hell. The chainfirer will need several days bedrest afterwards.