You seem like you are doing well already. You have a very high GPA and if you do comparably well on the GRE you should be a top pick I would think. Short of having worked in a medically related field, I can't think of anything more to do other than volunteering and shadowing. Also start thinking about who you want to get recommendations from. I would definitely recommend having at least one from a practicing anesthesia provider with a very favorable opinion of you. That's about all I can think of.