I would recommend you go through the drill with an experienced member of your unit.
safety wise -
roll some paper cartridges (tubes twisted or folded to keep the premeasured powder in) - keep the powder volume down, I always found 70 grains plenty for a .50, the crack of a rifle get attention in the line if you overload
Empty your bag of balls ahead of time, nothing but powder goes down the barrel, not even the paper, leave the ramrod alone.
elevate a little!!! don't shoot at the other line. And find out the limit to how close the lines may get.
for a new reenactor - the big thing is to ask the unit leader, have them show you the ropes and speak up if you have questions. Its a lot of fun, and safe if you use common sense