I personally found it helpful to commit a day towards visiting the optometrist area of practice. You are most likely to run into techs, who will relay the message for you (usually to no avail), but don't let that deter you. Some of my best experiences with the Dr. was established by the techs. Also, express your desire with friends and family. It's amazing the kind of connections people have on the down low.
I can't tell you what to do when you are shadowing. Besides common etiquette, Shadowing an optometrist can rang from just you observing, to a very active participation. It really depends on the Doctor. However, I would at least have a couple of questions towards the profession, just in case the Dr. is not that at all engaging