What should I do to transfer from CC to UCSC?

I'm currently enrolled at Irvine Valley college and plan on spending my third semester there this coming fall. My question: If I enroll for a semester at Cabrillo College next spring would I have a better chance for transfer admission to UCSC? And as for the TAG agreement, do I need to complete 30 transferable units with at least a 3.0 gpa before I begin my sophmore year or before I intend to transfer?