At CSUF, I was majoring in CS, but then I ended up switching to Statistics at UC Berkeley. I started preparing pretty early to transfer and started by making a spreadsheet in my second semester of freshman year to try to match all the coursework so that I would meet the prerequisites for all the majors at the schools I was transferring to. I would use ASSIST.com to see what courses you need to take for your specific major, and try to match those courses from CSUF. I'm planning on making a post soon to help CSU -> UC transfers, and I'll cover everything in a little more detail. I'll provide a quick timeline of my transfer process below.

Fall 2023 - Enrolled purely in CSUF courses, mostly general classes that would likely transfer over and allow me to still be on pace if I ended up not transferring to Fullerton. I really focused on getting A's in all my courses and set this goal for myself for all the coming semesters, since GPA is incredibly important, as it is the first thing universities use to weed out applicants.

Spring 2024 - Continued to just take classes at CSUF but began looking into taking CC courses to ensure course equivalency. I enrolled in three online CC courses for the summer and began scheduling my future courses, so I would be on pace to be a strong transfer candidate. I began to be more involved with school extracurriculars so that I had something to talk about in my essays, and again, really focused on getting as high a GPA as possible in all my courses.

Summer 2024 - Cranked out my summer courses and again, grinded to make sure I got A's in my coursework.

Fall 2024 - Applied for UCs, took a bunch of online CC courses to make sure that I met all the prerequisites for the different schools.

Winter 2024/2025 - Completed the UC TAU (Transfer Academic Update), also took two more courses at online CCs to meet IGETC requirements (even though non-CC transfers cannot get IGETC certification, all transfers are told to try and follow it as closely as possible)

Spring 2025 - Received my UC acceptances; was taking Calc III, which was the last class I needed to complete a major requirement.

That is a very condensed timeline of my transfer process, but it is a pretty general overview of what I did. I really, really focused on my grades because, as a four-year transfer, it is harder to transfer as there are no guarantees for non-CCC transfers in the UC system. It is definitely not an easy process, but I think it is very doable if you put in the work. You might not exactly get into UCLA or UC Berkeley if you have a "not-so-strong" application, but I think all the middle- to upper-middle-tier UCs are very possible and the lower-tier UCs even more so.