I majored in biology. I'd highly recommend doing volunteer work in areas you are interested in. That way you can (a) confirm you like it, (b) learn about it in more depth and (c) make useful contacts for when you are searching for a job. Volunteer work can lead directly to a job or it can give you the experience, contacts and references you need to get a job. All these things also apply to internships, so it's a good idea to apply for as many of those as you can. Volunteer work and internships look great on a CV. I found several opportunities for volunteer work in research labs at my university.
A friend of mine, who also majored in biology, took another approach. She sent letters and CVs to companies specialising in areas she was interested in. She now works for one of those companies in her favoured subject area.