Hi, Carlos-
Venice Beach has been a very popular place for buskers for a long, long time - but I think you have to get a permit from the City of Los Angeles (Venice is part of the City of LA). This page says a lottery started in 2005 for monthly permits for 40 spots for performers and 60 spots for vendors. Might be an idea to get started sometime other than during the summer, when permits might be likely to be scarce.
There are lots of small towns along the beach in Los Angeles and Orange Counties. Most likely, each independent city issues its own permits - don't restrict yourself just to Venice. Santa Monica, Manhattan Beach, Redondo Beach, and Hermosa Beach are likely places. I know the beaches in Los Angeles County quite well In Orange County, I'd try Huntington Beach, Laguna Beach, Dana Point, Balboa and Newport Beach, and maybe Seal Beach. In San Diego County, La Jolla and Mission Beach are good bets - I don't know about the north part of the county. I can't say whether all of these places permit buskers, but I've been to all of them and found them to be places that would be conducive to busking, if it's allowed.
Would you believe that I went to most of these places on official business as a federal government investigator....can't say I minded that part of my job at all.

Good luck!

-Joe-