I don't remove the nipple to place a charge underneath. If I remove the nipple (which I do after 25 shots or so) then I detail clean with alcohol the nipple and flash channel in the bolster or detail clean the powder drum.

Prior to going shooting:
Swab clean the bore and run a natural lube patch.
Pull the nipple and clean with alcohol inside and out and dry completely.
Then "fish" the flash channel in the bolster with alcohol soaked pipe cleaners to remove any oil. Follow with dry pipe cleaners.

Then grease (I use Birchwood/Casey Choke Tube Lube) the threads in bolster and nipple and snug in the nipple.

If your rifle has a powder drum, remove the nipple, cleanout screw and powder drum and clean with alcohol inside and out and dry completeley. Clean the drum port on the barrel with alcohol and dry.
Then re-assemble with anti-seize lube.

When loading, ensure that the lock is on "half-cock" to allow air to escape when loading powder and projectile. Otherwise then charge powder does not "collect" into the flash channel near the nipple.

Also, when adding powder "bump" the barrel 3-4 timesnear thenipple/bolster with the heel of your palm. This is to collect powder into the flash channel under the nipple.

On occassion every 5-10 shots use a nipple pick to clean the nipple port.
And remove the cleanout on powder drums and fish with a pipe cleaner.

RWS Dynamit-Nobel #1075 caps.

After several thousand caplock shots, I think I can only recall a handfull of times when I had a misfire and that was at the range. Those were due to cleaning when I either used too much alcohol or spit on a patch and forced liquid down into the flash channel near the nipple.

Otherwise I have never had a misfire in a hunting situation following the above procedure.

Good luck.

Tahquamenon