I also use clean rags to do my shellacking. I just use it dipped and wipe fast and light. I don't put it on heavy.
Once your existing coats are dry try some 4 O steel wool to even it up. Then put another light coat on it.
Oh and if you don't know this, you need to stir your shellac once in a while to keep it mixed up.
The Bri-Wax will not even out the shellac, but it will make it look nice.
Joe