I use Rascal's way and sometimes water bath, depends a bit on the liquid used, time in which I think it will be eaten and where I will store it (fridge or not)
Yes, botulism can potentially be a problem but the lid will bulge outward if toxins have been formed.
So common sense will tell you not to use it when that happens.
The botulism spores get killed at 116 or 120 oC (sources don't agree) but the toxin at 100 oC for 10 minutes (some sources say 8, others 15).
The botulism bacteria can only survive in an anaeroob environment with a pH of 4.5 or higher