With stock silica wicks you can dry burn.....as for ohms, the lower the ohms, the less resistance to current passing through the coil, giving faster heat up (watts, the measurement of heat at the coil for our purposes). If you are using a variable volt/watt device you won't have to worry so much that you didn't get a lower ohm coil, as on stock coil heads, you won't be able to go as high as your battery will put out before tasting burnt flavor. A good rule of thumb on variable volt is your coil can handle 2 volts over your resistance rating, for example a 1.6 ohm coil can vape at 3.6 volts...good starting point, make fine tune adjustment from there.
Another contributing factor to amount of vapor produced is your juice. Pg carries flavor better, but vg produces more cloud. So higher vg mixes will make more vapor for you. But using tanks, stay away from 100% vg, it is too thick to wick well in tanks with stock coils/wicks, and you will get dry hits