I'll speak from my experiences. My old store did an ALF last year that netted over 70 shots in that one clinic and they wanted us to come back for the rest of their patients. If you can sell yourself to a nursing home or ALF, you will get shots. Another place to consider are 55+ communities in your area. This year, my two communities near me have netted about 100 shots counting Prevnar. These places are typically Medicare patients (which means $0 copays usually), they have a community center where you can do the shots, and most are more than willing to get a shot that way since it is really convenient for them.
Beyond clinics, one way to generate increased shots at your store is to sell a shot climate. What I mean is people have an expectation when they get a shot that they will have to wait for some amount of time and waste that part of their day. At my pharmacy, my technicians and staff pharmacist know that flu shots take top priority. The longest part of most peoples' wait is them filling out their form. People love this as they come in, get their shot, and leave. What has happened is they tell their friends to come to my pharmacy since it's so fast. Also next year, all of these people will come back plus more from word of mouth. We have hit our yearly goals already 2 months into the fiscal year. Remember, people can get a shot for free practically anywhere. Why would they want to pick your store over any other?
Of course, you have to WANT to drive flu shots or none of this advice is worth crap. Patients know when you don't want to do something, and they won't come back if you aren't interested. It all depends on mindset. Oh, and holy thread resurrection!