With a lot of hard work over a number of years..!!!
Basically, you have to make the brigade an attractive place to be - create a perception - and a reality that the brigade is a nice friendly group of people, and that the brigade is a professional group of people (so people want to be part of it!)
Make personal contact with people within the area that you meet up with, and tell them about the brigade, and invite them to come along at any time.
When there is a BFF-1 Course coming up (or you anticipate one) let your community know that - eg via a blackboard / sign outside your station saying something like "Training Course for new members starts soon. Come and see us Monday nights from 7.30 pm " - or other messages that might prompt people to come along, or target new members in the community - if you know they have just moved in, go and visit them, welcome them to the district, we are a nice bunch of people etc etc, oh, and by the way, come and join us. Some times they do (but it might not be that year) sometimes they don't / can't, but if you do the right thing, they think you are a nice bunch of people, and you have their support
Let people know when you got to calls, and what you do - eg a blackboard outside the station, which lists basic details of the last call you went to - if you do it for all your calls, people start looking specifically at your notices
Create a social atmosphere in the brigade - we have supper after training each night, a mid year & a Christmas show, and we are just about to restart our "Sunday Socials" - basically, all the members AND their families, are invited to a brigade members house, they bring a plate of food to share, some drinks & a chair, and just have a social afternoon. We did these a few years ago, when we had a big influx of members, and are restarting it due to the next influx....
Recruiting new members can include targeting other members of the family - so including them in social events can provide even more of a benefit!
These are some of the strategies we have employed to recruit new members. It is not a quick process, but the results have been very pleasing...
Pip