If you are an advanced vaper who is looking for coils that can produce the biggest clouds, here are some coil types for you:
Dual Coil 24 Gauge
4 wraps on each side will ohm you out at 0.16 ohms. With the correct battery, it can be used on a single tube mod as well. The ramp-up time is comparatively quick and will create a massive cloud.
Parallel Dual Coils
8 wraps on each side will ohm you out at about 0.14 ohms. As you have doubled the wire, you will also have to double the number of wraps. This build requires a parallel box mod, as the ramp-up time on a single will drain your battery real quick. Also, if the wire crosses at any point, it will give a hot spot and short inside the coil and might cut the coil, so you will have to start over.
Twisted 22 Gauge
8 wraps on each side and it almost looks like the parallel build, but it looks much better.
18 Gauge Continuous
6 wraps on each side of the center post. You can use it as a mechanical mod, but it is best not to try this if you are not an experienced cloud chaser who knows how to pulse your battery.
Clapton Coils
Clapton Coils can produce great clouds and great flavor. These are almost always in stock in the local shops. These are pre-made and ready to install. These are the only coils you might want to buy ready-made because the process is a bit too complicated.
Finally, do not try these on your first build. Take it slow and learn what you are doing carefully.