Your nic salts were pretty high, so I'd say that 6 m.g. is probably fairly reasonable, but you may have to experiment a bit to figure out what gives you a nice balance. Some folks starting DL choose to buy a slightly higher strength like 9 and the same flavor in 0 so that using whatever ratios of the two liquids will allow you to experiment with your levels more precisely. Etc. It's quite often not a bad strategy at all.
Good luck,
Anna