Word-of-mouth is the biggest and best ad network. The website has to be there to show people that you are a real organisation rather than an unknown man and van, but don't assume it will bring in loads of traffic by itself. Less is more - use it to say what what do and how to contact you but don't harp on about how customer-centric and wonderful your service is. Make it simple, clean and accurate (you're looking for business, not buisness) Likewise, make sure any local directory listings that pick up your details show up-to-date information.
Do a good job and charge proportionately from the outset, accepting that you will occasionally have to suck it up when you make a mistake. As mentioned above, too low a price helps no-one; the customer wonders whether they are getting second-rate quality and you struggle to keep afloat. This is a mistake I made early on, I did high quality work but set my rates too low and had difficulty completing work on time etc because my cash flow was too shaky. It took a while to develop the confidence to charge what I needed to charge to justify the quality of work, but when I did, the only jobs I lost were the ones I didn't want to do anyway. Once I was able to offer a more reliable, faster service, the work was just pouring in.
One of the good things about offering a commodity like electrical contracting is that there is a fair percentage of customers out there who are ready and willing to pay for a decent service, without you having to justify it. You are not offering rabbit yoga or on-site turnip carving, where you have to convince the customer they need you in the first place. Be available; do what they expect plus a little more; prove you're a quality act and don't soak them; and the work will build up as quick as you like.