Have office hours when people are off, i.e., in the evenings and weekends. If the other vets in the area only see patients for a few hours on Saturday mornings, then I'd schedule your availability for Saturday or Sunday afternoons.
Be as warm as possible with the pets and their owners.
Have a pleasant waiting room; make certain there is adequate parking and that getting in and out of your facility is easy.
Make certain the equipment is clean. I walked out of one practice where the equipment did not seem very clean.
Get an excellent office manager and vet tech.
Know something about pet diets and nutrition, not just the one class in vet school. As more and more people either feed raw or freeze-dried and reconstituted with water diets to their companion animals, we'd like a second opinion on this practice. Too many recalls out there for comfort, and too many fillers in packaged food (just like human food -- lots of junk). Try to avoid selling a line of food on your premises; I'd prefer a good five minute discussion on the ins and outs of pet nutrition.
The BWI area is one of the larger concentrations of highly educated people in the US; please tell us the facts, or if you don't know, make a referral to someone who can.