A crucial first step is to build a strong contact list for media operators in your area. Your list should be made up of anyone who has an audience, such as a newspaper, magazine, tv channel, radio station or website, and who will cover you (at least somewhat) favourably.
In your local area you should be able to identify a key local paper. Some constituencies are well covered by just one, others have a few which cover different corners of the area. You should also be able to identify a number of key local broadcasters - BBC and ITV/STV have regional TV coverage everywhere, make sure that you have direct contact details for your local political correspondents for at least your main newspaper and these two TV broadcasters. In England, BBC local radio is comprehensive and they will give you airtime for your smaller local campaigns, because they need fresh content each day. You will typically find a myriad of super-local radio stations operating in your area, along with increasing amounts of bloggers and Facebook moderators, who should all be on your contact list.
Each one of these contacts has an audience which you can tap into; the more places you are being broadcast, the more people you will reach. It is very important to ensure that you are working with the mainstream TV, radio and print media, but do not ignore the smaller, ultra-local broadcasters, as they can grant you access to much harder-to-reach audiences.
Once you have built a contact list, you next need to harvest their contact details, especially email addresses. Contact each person directly and make sure that you have their permission to be on your list, which you will use to distribute your press releases and op notes. Once you have built your list you are up and running, and can send them information about your campaigns, events and achievements.
Try to keep your key local journalists warm with some kind of contact each week or fortnight. This can be through sending them stories, or alternatively sending responses to local news stories. This will help remind them that you are there, and increase the likelihood that you receive fair or favourable coverage.