Not that I know everything:
Having said that I cast my first RB at 14yrs old~
Clean you barrel and nipple with alcohol before shooting.
Run a damp patch of alcohol down the bore. Leave it , the rod and patch; in with he ramrod.
Fire a cap and it will blow the crud onto your patch. Pull the ramrod out place a clean patch on and run it down again to dry and clean out the rest of the debris. Give the nipple a poke with a wire to make sure it is clear. Let is all dry out while you fiddle around setting up to load.
JUST before you load~Fire another cap while the muzzle is pointed at the ground. You should see the grass or dirt move. If that happens your clear and ready to shoot. I have see guys fire off a blank load , but IMO that really cruds up the bore. As far as firing a cap off in your hood , it all depends on who sees you. just do it in the garage with ear plugs in.
I've been following this process for several decades now, ESPECIALLY shooting a paten breech barrel.