so, you are gonna become somewhat familiar with basic electricity by being a vaper, if you aren't already.
The resistance (ohms) of the coil determine what wattage can be run through it. The higher the ohms, the lower the wattage needed to get it to create heat. Any coil under 1 ohm is considered 'sub ohm', since it's below (sub) 1 ohm. A .9 ohm coil is still a 'sub ohm' coil, but it's way different from a .2 ohm coil.
A .9 ohm coil might run at 40-60w range, but the .12 ohm coils I use have a range of 120-220w.
There's a minimum wattage needed to get the coil to even heat up, so you can turn the wattage down to an extent, but not totally. Also, it takes longer for it to heat up enough to actually vaporize the liquid, this is called 'ramp up' time. So, if a coil's range if 50-70w, you could theoretically still get it to hit at 45w, but it'd take a bit to ramp up and it'd be real weak clouds.
To create bigger clouds, you want lower ohm coils with higher wattages. There are various reasons for this, and the surface area of the coil factors in, but one of the main reasons is it heats up quicker.
It sounds like you should just get some regular high VG juices, figure out what flavor you like, and stick with that for now. Salt nic stuff is relatively new, and seems more for experienced vapers that are looking for a specific thing. I don't know anyone that really uses them regularly at my store, for example.