Popular drugstores tend to share bigger part of the pie in retail pharmacy. They are more equipped and well-marketed all over the country. Having said that, the emerging new pharmacies will be making a gamble when located in areas with big "M" (I know you know what I mean).
In opening a new drugstore, the word of the mouth is important as well as gimmicks to attract customers. Give-aways, discounts, membership, and promotions will also do the trick. Sometimes music and mini buffet can call attention of people to check out the store. But free food and lively music is everyday. After that you must have a strong marketing plan to beat your competitors.
As for my personal opinion and experience, 4 P's must be maintained to keep you going.
P - price (price must be right and competitive)
P - professionalism (well-mannered, people oriented staffs)
P - products (availability of goods)
P - Pharmacist and Staffs (well-trained and loyal people that you can rely on)
Even before you open a pharmacy, another P is needed - Planning. Take your time, don't rush to make it right.