Every interaction you have is an opportunity to expand your network. Your network should include people you can go to for advice, assistance, reassurance or friendship. Nobody can make it alone; a support network will help you get more out of your Cal experience.
Meet your classmates, join clubs, go to social events, study in cafés, and do things that keep you interacting with new and different people. Be approachable and don't give up, even if takes a while. Your goal is to makes lots of acquaintances, some of whom will eventually become good friends.
Find a community.
Get involved in programs and organizations that bring students together around a common interest, such as an academic field, community service, ethnic/cultural background, or religion. People who share similar values with you can provide much-needed support and encouragement when things get tough.
Seek staff mentors.
It's especially helpful to have a couple go-to people at Cal who you can count on for advice and support. Identify someone you admire and respect, or tap into pre-existing mentorship programs. Meet for lunch every month or two to share the highs and lows of your semester, and seek advice on how to manage challenges and make progress on academic or career goals.
Share with your family.
Parents, grandparents, aunts, uncles, siblings, and cousins can be a great source of moral support, and they are usually rooting for you to do well in college. Keep them updated on what you're doing at Cal. Let them know how you're growing and changing. Invite them to visit you, and don't forget to tell them you appreciate them.
Fill out this Mindmap (pdf).
Get some ideas about who's in your network and who should be!