HI Dopeh,
All I do is mix 50% PG with 50% VG to get my base at 25 mg. THen I add menthol drops that I made from menthol crystals. I crush the menthol crystals up real fine and then fill a 3ml bottle about 3/4 full with the crushed crystals then add PG to fill the bottle. THen I place the bottle in hot water to warm everything up and then shake the bottle to desolve the crystals. I add the menthol drops to the PG/VG mix. For every ml of base I add about .7 to 1 drop per ml of base. Just start with a few drops, maybe .3 drops per ml, and keep adding to you get the hit you want. I don't know if anyone would like this but me as juices are so subjective but it works for me. For variety you can add flavors, such as Capellas, to the mix. I've used Vanilla Custard (capellas).
I bought some 100 mg PG as a base. What i do is mix 10 ml of this with 10 ml of PG. THen I mix 20 ml of VG to this. So I end up with 40ml of 25mg in a 50/50 mix of PG/VG. Then add the drops to taste.