OK, Temp control is built in to many mods these days - The mods can be run in Power mode or TC Mode depending on your mood - but for TC mode to work you will need a coil in one of the TC compatible materials - Namely SS316, Nickel 200, Titanium, or NiFe30. There are a lot of prebuilt SS316 coils available so they are a good choice as they can safely be used in both power and TC modes with no issues at all.
Temp control isn't for everyone, but I use it almost exclusively. Basically instead of setting the wattage level that the coil fires at you set a temperature for the coil to run at, the mod then controls the power output to maintain that temperature. If using store bought coil heads it should be pretty simple but if you build your own coils it's a little more involved as the coils need to be well made and the wicking needs to be not too tight and not too loose...