I have Legal Muscle, Secrets of Mail Order Success, among other books.
There's a little bit of information that can be gained from each title and the more knowledge that you have - the better.
Did I learn anything from the book? Yes - I did learn of a source, but that was mainly all since I had already read Legal Muscle. But even Legal Muscle just put out a few basics . . .
I guess I expected more from BOTH BOOKS . . . but basically here's the jist of it all: Don't sign for anything, check your state laws, if they want you, they'll get you OR they'll just send you a letter saying - Go Ahead, Contact Us for this Package and if you do, you're Fucked, that traveling to Mexico may or may not get you drugs, blah blah blah. Basically - you'll either be ok, or you'll get a little slap on the hands, or you're fucked. There didn't seem to be any ground breaking information coming from either book . . .
For source information, look around - there are a few websites that you pay for and can get the info . . . although there is one really popular source listed in the Mail Order book . . . but other sites offer more information . . .