In my unexperianced thinking I would disagree overall about that advice. Depending on the night, most servers are too busy to sit there and watch you do a few tricks (and if they aren't I know that the manger would be). I mean thats just not the professional way to go about getting a job doing magic at a restaurant. Here's some intelligent thoughts:

call and see when would be a good time (when its not busy) to see/talk to the manager

go in during that time and ask for the manager, tell him/her who you are and how YOU CAN HELP THEIR BUSINESS

don't talk about it, be about it; show them some effects (lately i've become a fairly big fan of the hot rod I think its an awesome quick and magical effect) 2 of my other routines that I like a lot are:
1.
-Ambitous Card (a combo of my own and Bill Malone)
-Club Sandwich (Use their signed amb. card and the needed force card)
note: I leave the jokers in the jokers in the box and then pull them out to "find" the two selections
- To end this routine with customers I would say "let me show you something with my pen (pen thru nose and out mouth) does anyone have bill, the bigger the better" pen thru dollar
note: you have your tip in your hand
2.
-Scotch and Soda
-Ring Leader
-Invisible deck
(I know I know it doesn't seem to have an apparent flow, but S&S has a definite and clear ending so after it I would just be like, "can I borrow your ring" as the awe from the effect dies down.
Amaze them with Ring Leader and say, "I usually do a few card tricks at the tables and I haven't done any for you guys, would you like to see my best card trick before I go. Alright here's the deck...")