my 2 cents
Practice in your back yard with your net you will get good pretty quick. There is a video online on the Calusa net website.
http://www.calusa.com/howtothrow.cfm There are about 4 ways that I know to throw one but the method shown on the web site (same shown in the fishermen I think (I just took a glance at it) ) is probably the best all around way to do it.
Nets vary a lot. Catching bait requires the right net. You need the the right mesh size and sink rate for different baits. For bunker you need a fast sinking larger mesh then for silver-sides or peanuts. After you throw the wrong net a few hundred times then try the right one there is a WORLD of difference. So keep that in mind. Lots of info on that site about the right net. Stay away from those cheap sub-$10 cast nets, they are not worth #^^^^& and throw like a bunch of junk and don't sink worth a damn. I can't tell you how many times I see guys struggling to catch bait off the dock with one of those. (When I was a kid that is all I had...when I got a good net I could not believe the bait I was catching) It is just a little practice with a half way decent net.
Goose said one thing that I think is a killer bait and largely overlooked these days...chogies. We called them Bergalls but they are the same. These damn things work. This was my fathers favorite bait for bass. When he retired he would catch a bunch of these near an inshore rock jetty and live line them off Shagwong reef off Montauk. Bass attacked them. No regulations or hassles fishing with chogies and they are pretty rugged.
Also, keep in mind that if you have a net greater then 8' radius in your boat you need a commercial bait endorsement on your license, even if you don't plan on selling bait. I think the reg states any net with over 200 sq ft and you need the permit. With the bunker coming back somewhat the environmental police are checking again, (once they check you and know you they seem to leave you alone)
Once you get the hang of it you will have plenty of quality bait, it just takes a little time.