You'll want to make sure that enough of the potential customers you've identified will actually choose your business.
Much of your work is likely to be repairs or installation of new wiring and fixtures in domestic properties. For these jobs you will be competing against other local electricians, so you must try to attract potential customers. Many will make their choice based on price so make sure that your rates are broadly competitive with others operating nearby. Price isn't everything though, and potential customers will also consider your reputation, the level of service offered and whether you are able to carry out the work at a convenient time (often as soon as possible). Even things like tidying up thoroughly after you can make a big difference. Word of mouth recommendations from satisfied customers may well be a key means of obtaining new work. You could also consider signing up to an online customer feedback and work referral service such as Rated People, or a vetting and review website like Checkatrade. There are various government-backed vetting services for trades-people that you could consider too, such as TrustMark and Buy with Confidence - Trading Standards Approved.
Many domestic customers won't need the services of an electrician very often and some may not have the name of a reliable trades-person to hand. Think about how these people are likely to locate a suitable electrician - will they turn to the telephone directory or search online, for example? If they're looking online, are they most likely to use a search engine, an online directory or a referral website? Of course, different people will do different things, but you'll need to make decisions about how and where to focus your advertising and marketing efforts.
Bear in mind that it's quite common for local residents to approach trades-people when they're working in a neighbourhood and ask them to look at a job that needs doing. So it's important to make sure your van is easily noticeable, your staff are polite and approachable, and that you're able to give them the information they need about things like price and when you could do the work.
Some of your domestic customers will know that certain types of electrical work need to be either signed off by an approved competent installer or checked by a building inspector. These customers may well prefer to use someone who is approved to sign off their own work where necessary.
Try to build up contacts with local firms like general builders and shopfitters and let them know that your services are available. You could also try getting on the list of approved contractors used by your local authority, or other organisations such as hospitals or universities. Let them know what services you offer and ask for details about tendering for contract work and any special requirements (such as qualifications and quality standard certification) that you might need in order to be considered.
Your market research might indicate that there is a gap in the market that you can fill. For example, perhaps no one in your area is specialising in installing security cameras or burglar alarm systems. Whether or not you decide to specialise in a particular type of work, try to emphasise the quality of your services. Joining a trade association quality scheme will demonstrate that your business is run to a high standard. Similarly, a friendly and knowledgeable approach will inspire confidence in potential customers. You could give some basic electrical safety tips and advice on your website. Making suggestions and offering advice won't cost you anything, but might help persuade people to choose your business.