Essentially, the script that erases perks when you delevel as you leave Goodsprings only seems to check for level 2 perks. Ordinarily though, there's really only enough XP in the Goodsprings area to get to level 3 without a lot of tedious waiting around for Gecko respawns - and once you've levelled up a few times, it's a lot of tedious waiting around.

So, while it's possible to get a free perk or two if you are, for instance killing everyone, it's really more effort than it's worth to go out of your way for without abusing the aforementioned infinite XP glitch. Once you do that however, basically, the way it works is you hit level 30, walk out of town, and choose to rebuild your character. This allows you to reassign your perks and skill points, delevels you to 1, and awards you an amount of experience equal to what was removed. Not all perks are stripped however, and thus you effectively double your perks.

Essentially, the script that erases perks when you delevel as you leave Goodsprings only seems to check for level 2 perks. Ordinarily though, there's really only enough XP in the Goodsprings area to get to level 3 without a lot of tedious waiting around for Gecko respawns - and once you've levelled up a few times, it's a lot of tedious waiting around.

So, while it's possible to get a free perk or two if you are, for instance killing everyone, it's really more effort than it's worth to go out of your way for without abusing the aforementioned infinite XP glitch. Once you do that however, basically, the way it works is you hit level 30, walk out of town, and choose to rebuild your character. This allows you to reassign your perks and skill points, delevels you to 1, and awards you an amount of experience equal to what was removed. Not all perks are stripped however, and thus you effectively double your perks.