Well, your GPA makes you a good target for most mid-level / boutique consulting and banking firms. Getting your foot in the door at the big names might be tough, but you can establish a killer resume to boost your chances of making it past screeners.
Joining the business fraternity (what, PGN?) won't be helpful since by the time you finish pledging, the best jobs will have been given away already. Study abroad in China is a great boost to your application, presuming you speak at least proficient Chinese, and it will certainly open doors to you.
For right now, you're not behind - you're right on schedule. It's good that you're thinking about this at this stage and not six months from now, when it would be too late already.
Do some research. Look at UCSC's career services website, and figure out the companies that recruit at your school. Then do some research to figure out what these companies actually do. Look at job descriptions and job postings (many are probably already up!) for on-campus recruiting positions. If you don't know what you want to do, then it might be good to just apply for everything that even piques your interest.
Without much going on this summer for you, you should be able to dedicate yourself FULLY to learning about potential employers... if you're not spending at LEAST ten hours a week honing your resume, researching companies, figuring out interests and developing cover letters, you are not doing enough.
Fall recruiting happens as soon as you get back to school. You should be prepared to apply before you step foot on campus again, and once you start, you'll find all of the application requirements. During my senior year, I literally spent 30+ hours every week for 10 weeks working on job applications, interview prep, interviews, post-interview etiquette, etc. It was ridiculously difficult and made college applications look like a joke, but it was WELL worth it!