I went back at 28 or so and took my prereqs... I was a business major but really enjoyed the science courses. I found I liked the ones everyone else hated -- biochem and organic chem. My experience may be different b/c school is a joy for me. My and my classmates didn't have much in common, to be honest, so don't expect to hang out w/ them outside of class. I think they looked at me with a little bit of derision. Eh, what the hell do they know anyways, right?
I did some volunteering at a nearby hospital, your premed office should be able to point you towards something. If not, just call the volunteer office of your local hospital and tell them what you want to do. I also ended up doing some research in my biochem profs lab. If you are enthusiastic and forthright, you should be able to find somebody who needs a hand in their lab.
Now I'm thirty, working full time to pay the bills, and have had seven interviews. I was surprised to find out that being older is not the big deal you think it might be. Most interviewers don't really mention it and if anything they seem to view it as a positive attribute. Just be honest and things will work out. They will lump your old gpa into your new one. In order to be more competitive, you might need to take more courses to bring the overall avg up.
