One of the most important things to know when learning how to Float-rig fish is setting the stopper/Slip knot at the proper depth.
General rule: Always set bait (live shrimp) about a foot off the bottom.
Then folks ask...."how ya do that at the jetties?" Real simple! Set the bait so it travels over the jetty rocks. What ever the depth is you are anchored at and the current is heading, then shorten if you catch rock and lengthen if not deep enough, which means you're recieving not bites. A good float fisherman, especially at a place like along the jetties is always fine tuning thier depth as they fish.
Then, there's the best way to make a stopper/slip knot that sets your float at the desired depth.
Some float-rig fisherman use rubber bands, some use mono, and some use the pre-made stopper knots that you can buy that come on the lil' tube. I like these. They hold really well on super braid line. But when in a pinch, I always drop right back to a 20# mono stopper/slip knot.
Then the next question is, "how do you make (tie) a stopper knot." Well, I've been searching for about a year now for the best diagram I could find. And I just found it on a very cool products web site.
Here ya go: http://www.wigglefin.com/knots/fishing_knots.html and yeah, check out the Wigglefin Idea while your there. I'm trying a few for the heck of it too.