Make sure the "juice" you put in them is good, dont get the ones that put you on a filter "subscription" get the ones you put drops in. Try an assortment pack of flavors so you get one you like. I got a bad flavor at the beginning and now I could puke just trying again. Its not the cigs its like the "aftertaste". You can get strengths so strong it can make your head spin, and then ease down from there. I think thats what it takes to switch if you ask me.
If anyone is interested I got two 501's (not sure 512's maybe?) that I would sell, you would have to get the juice. Both have-Charger, 2 batts, and 5 cartriges only used em like a month. Just PM me.
Lastly have you gone to Totally Wicked?