Transfering from a CSU to UC

Hello everyone, So I am a freshmen( last quarter to become a sophomore) at CSUSB. I wanna tranfer out to UCLA/UCR/UCI. People are keep telling me how hard it is to transfer from a CSU to a UC. Soo, i was wondering if I start taking classes at CC beside CSUSB. Would that affect me possitively and would I get priority consideration in admision to UC. Or would I have to completely leave the CSUSB. And become a full time student at a CC???

Thanks in advance if anyone replies.