If you grab some of each strength, 6 & 12, as long as they are complimentary flavours ie. Vanilla Custard with Banana (or almost ant fruit for that matter), if straight 12 is too strong
you can dilute the strength with the lower mg liquid.
If there is a single flavour you know you like it also never hurts to have it in 2 or 3 nic. levels for your changing needs throughout the day. ie. 3mg, 6mg, 12mg. Cheers.