Any chance on damaging the mod while practicing building.
Yes, you could damage your mod and yourself if you do any of the below.
1. You build a coil and fire it on a mech mod without measuring the build.
2. You build a coil that exceed the amp rating of your battery.
'In other words, you need to read (and understand) all about battery safety, Ohm's Law, amp draw, etc if you are going to be using a mechanical and/or a rebuildable. The safest way to start would be with a regulated mod and a rebuildable.