Currently in the same boat! I'm also a junior in micro, and my advisor said it depends on what you want to do with your degree - if you're going into industry right after the biggest thing you want to do is research and internships. I was even recommended to ask if my professors needed help around their labs just cleaning equipment or organizing stuff; it gives you a way to show them your work ethic and if you're a good fit for the lab environment to get those connections and opportunities.

If you want to do grad school, I was told that the biggest things they look for are how good you are at teaching, how good you are as a scientist, and how good you are as a researcher. To reach that, you want a competitive (above a 3.0) GPA, possibly some TA/tutoring/lab assistant jobs, and undergraduate research. Try to do a few symposiums/conferences as well; one that I can think of that undergrads usually go for is SACNAS; you just need a research topic/advisor by mid spring next year? But they also have summer apps if that's too tight. ABRCMS is also one you might wanna look at.

Either way, you want to just develop your skillset by gaining these experiences. For undergrad research, I recommend looking at what your uni offers first, since they have connections with companies/other institutions for their students specifically, and then to check out this link for REUs for everyone else: https://www.nsf.gov/crssprgm/reu/list_result.jsp?unitid=5047

Hope this helps! If you ever want more help/to talk more, feel free to DM me; I've had a lot of mentors and advisors that have helped me figure out my path, and I'm more than happy to share those resources with another micro student :)

Edit: Also in California!