What you need is a nipple pick. Actually its a good idea to pick the nipple between shots. If you don't have one, an old guitar sting will work. Even the stiff twist bread wrappers (peel the paper back)although they bend kind of easy. Depending on the nipple sometimes if you straighten out a paper clip it will clear the nipple but it will not pass through the flash hole into the bolster. For that you do need a nipple pick or stiff wire of some sorts.

The nipple pick will move the paper out of the way and make sure the flash old is clean. Another way is to swab between shots as the pressure from the swab will blow the debris out of the nipple.

One last thing that is now considered a NO NO!!! is after you shoot, cock the rifle and blow through the barrel. This will blow the embers out in the breech if there are any, and blow the smoke and crud out of the nipple. Don't get caught doing it at a public range though....

Good luck.