Personally, i am a 5V vaper, just preference. I am an atomizer/dripper person. I usually use the standard 510 atomizers, before I use them I blow out the primer that is in all atomizers (not sure about cartomizers)...The primer is a very nasty taste. I also remove any wicking material from under the bridge...can also lead to burning taste.
When I prime an atty I am using for the first time...I add 4 drops of liquid and then add a drop or 2 if needed. For me, dripping gives me the best flavor, throat hit and vapor when I am using 5v. I haven't had too much trouble with different liquids. I know there are vendors that sell HV liquids (not sure of names), but I just use standard liquids.