For stick baits or Senko's I use this formula and it's pretty spot on.
4 OZ. medium plastisol
2 tbsp. softener
1/4 cup salt ( 4 tbsp.)
4 drops black colorant
.035 black glitter (desired amount)
.08 gold glitter (desired amount)
.08 silver glitter (desired amount)
I try and not put too much of the silver and gold glitter as it goes a long ways. You can also substitute the above formula by using 2.5 TBSP Glass bead media, 1 TBSP softener and 2 drops of black. GBM does not cloud the bait as much.