Step 1. DO NOT use one of those oversize self-tapping drain plugs! You will most likely have a permanent leak thereafter if you do!
Step 2. First try just a new plug! At least on newer vehicles, the pan insert is much harder than the plug so when Harry Hammerhand gets to it, he strips the plug and not the pan. A new plug and you're good to go. In the past 25+ years as a mechanic, I have not had to use one of those evil self-threading oversize plugs but end up with a good-sized handful of stripped plugs every year.
Step 3. If it is your pan that is stripped, go to a good parts house and ask to see a catalog (Dorman, maybe) of drain plugs and find one the next size up (it may be metric). Get a tap that size and drill and retap. If you aimed the drill right, no more leaks.
This is assuming you have a later model with a regular sized plug. If you have the early large-mouthd plug, it may be necessary to drop the pan. A 'farmer fix' here may be disasterous.