i have bought cheap cast nets and basically use them for practice. check out the web and get a good net with adequate weight otherwise it is useless.i have fitec and calusa nets and have several. a bunker net with 12'spread and 2"mesh very heavy,a 10'1/4" for peanut bunker and spearing and a 1/2"for use in florida on ballyhoo and general purpose. again dont waste your money on a cheapnet. check out netco for good prices.
If you get a Cabelas or Bass Pro shops catalog they should be in there. As for advice, start out with a small one maybe a 6 footer and as you get more comferable with it you can start to get bigger ones.