First 20 to 30 gr is the commen load. If you use a light load the a wad makes a nice filler.
You need: to prevent chain fires[all chambers going off at the same time]
the normal way of doing this is either to use a wad under the ball or grease over the top.
Accuracy:some like different powder charges some have a bit larger or smaller powder capacity.Using wads or filler such as corn meal over the top of the powder and under the ball seat the ball[or bullet] just below level with the top of the cylinder.
Check that you have the right size caps some take #10.
Hope this helps Lee