I only use manuals. Manuals are harder to damage or kill with juices leaks and make it easier to get a good hit. I tried an auto (like G6) and to me it sucked compared to manuals. I had to take 2 drags into my mouth with an auto then inhale to get the same hit as 1 drag on the manual.
You press in the button 1 second before you start your drag, start dragging, let up the button right before the end of your drag, inhale. And no you cannot just drag to make it work.
Most people on ECF use and recommend manual batteries.
And you do NOT dry burn stuffing cartomizers.
If you want to test juices on a manual KR808D-1 (like G6 manual) use a standard resistance DSE901 atomizer and drip tip (LiteCigUSA.net). And only put juices you know you like that have suitable thinness, into cartomizers. I use PG w/ 10-20% VG and I avoid juices that drop a lot of flavoring sediment.