From a safety perspective, there's not a whole lot to it. What specifically is giving you the trouble?
1: Your battery has an amp limit.*
2: Don't go over that limit.**
*(Don't go by what it says on the cell's wrapper or vendor's website; check
@Mooch's blog for his latest charts and test results and choose an appropriate battery from a trusted vendor.)
**(The amp draw of your device is a simple arithmetic calculation. We always use "worst-case" voltage for safety purposes, so you don't have to measure your battery to find out what the voltage is. Just assume it's either at full charge of 4.2 on a mech, or near cutoff voltage of 3.0 on a regulated [for single-cell devices. Multiple batteries make the calculations a
bit trickier, and can go one of two ways depending on whether they're in series or parallel.] On a mech mod, the amp draw is [4.2 volts] / ["???" ohms], on a regulated it's ["???" watts setting] / [3.0 volts].)
On a mech mod you should also familiarize yourself with the current path and exactly how the energy is going to transfer from one end of the battery, through (usually) the body of the mod or (sometimes) by some other method up to the atomizer, through the coil and back into the battery, and also how the switch operates. Becoming familiar with these aspects of your device allows you to more effectively check for and prevent potential short-circuits. Keep the device and especially all parts of the circuit path clean and debris-free, and
always check the atomizer's resistance (with the top cap attached) on a regulated device or stand-alone ohm reader before firing it on a mech mod.
This should be enough to get you vaping safely, at least. As for where to go from there, well, that's a much longer post.
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