Chris "Basic Fantasy Role-Playing" Gonnerman has written an RPG Primer.
You can find it in print at Amazon, here:
Or download vers. 16 for free here:
Basic Fantasy Forums
I've gone with the free version, since I rarely need to refer back to print versions. But it might round a nice "boxed set" gift to someone just getting into (or interested in getting into) RPGs.
It's good advice in general and worth the time to read it.
And if you're interested, I reviewed the Basic Fantasy Role-Playing game here.