Watch out for heisenberg/menthol?/liqourice juices. The flavour tends to stick around way past the tank emptying tainting other juices.If you're swapping juices around, try and stick to similar juices per tank. Fruits with fruits, custards with custards etc, as some flavours vastly different can taste like vaping arse.
If you are a mouth to lung smoker, look into buying a decent rebuildable tank atomizer. You will learn to make your own coils, save a ton of cash (not buying coils), and the flavour is so much better than even the best tank with disposable coils, (i'm unsure why that is, maybe it's just me?).
Have a look on gearbest, or fasttech after researching well made clones of expensive atty's, and some kanthal wire, and a cheap coil kit and you are good to go .I bought a Kayfun mini v3, and the flavour is grand (
http://www.gearbest.com/rebuildable-atomizers/pp_427859.html)
Lastly be careful you don't spend too much, I've two RDA's on the way, diy concentrates, 4 mods and another on the way, 8 tanks in the front room, and a kidney on it's way to China to pay for it all.
If any of the above is utter shite, my apologies, i'm a bit of a newb myself. It may be worth researching further any of the points I made.