I don't have time for a super-detailed post right this second, but will try to get to it later tonight. The blu is not for heavy smokers, and your main concern is going to be vapor and throat hit, a 510 might well be better for you. But the blu has a largely undeserved reputation for being woefully underpowered, when in fact if you use it the right way, it can be pretty startling for such a tiny device.
Quickly, the things that have made the most difference for me are:
1) Refill the stock carts with good liquid. So far I'm liking the Johnson Creek reduced-PG liquids best.
2) Restuff the stock carts with better filling. The difference when using the PET from Lipton Pyramid tea bags is astounding. It wicks the fluid faster and more thoroughly, and more fluid to the atomizer = more vapor.
3) Buy extra atomizers-- not because they die particularly often (I haven't had one die yet), but because they're cheap and you can use them to cap refilled blu carts and carry them in the pack that way. You can carry six different flavors and not worry about overlap, and you always have moist, ready atomizers when you switch flavors.
4) If you don't mind leaving behind the convenience of carts, you can try dipping (not dripping, as that's less convenient and more of a risk to your equipment). Carry the liquid of your choice in a contact lens case, and dip the atomizer wick into the liquid for a couple of seconds, then replace the mouthpiece and you're good for maybe a dozen draws before you have to dip again. This will probably yield the best vapor, but I stopped because carts are so much more convenient, and after the PTB mod, the performance difference was negligible.
A last piece of advice: the one thing you're going to hear most often is "return the blu and get a [510/901/Prodigy/etc.]." While that may in fact be the best move for you, depending on your habits, needs, and requirements, if you take some time to get to know the blu, you may well find that it performs very well when you treat it right. For reasons I still don't understand, the blu forum here is populated largely with people who seem never to have even used one, and this will become obvious quickly.