The line of html that AS provides in that Help link is great! You can just copy it, slap it in an e-mail, and it has your AS username already in it, so if the person signs up from the link they automatically credit you.
I hate being pushy, so I like to write my own rather diffident and self-conscious text to go along with it
Using the html line, there's no added text I didn't put there myself. It's not fancy, but it works!