A job as a research assistant

Does anyone here have a job as a research assistant..and if you do, or know someone that does, what did you major in? Im going back to school and I really want to persue a career in medical research..and I was thinking my best bet is to focus on biology, however, I noticed a lot of research jobs mention any kind of life science..so I guess I just want to know what a person in the field suggests..and tips on getting a job..like if you should volunteer first somewhere etc..

I do but I'm working in the psychology dept.
Big universities, especially those that have a med school, will have plenty of research labs...
Hmm well honestly it will probably be a little easier to volunteer first so you have that on your resume, I would start applying for jobs (go to the uni website see if they're looking for anyone) but in the meanwhile find out who is doing what research and ask if they need any RAs... you may get a job offer, or you may be told they cant pay you but welcome volunteers...