Google is the best for me but I am in a different business to you.
Like others have said you have the old school marketing e.g. word of mouth, leaflets paper etc and then the online marketing campaigns e.g. google.
A lot of my friends who are working in the construction industry still say the old school methods are the best especially word of mouth, What @Sellers said above is very effective in my eyes and I still do it now, each time I see an Electrician in public, I introduce myself and my business even if I am in Tesco shopping and an Electrician is carrying out some maintenance. One little trick that I know a friend of mine uses is a Fridge magnet with his Company details on it, this is great if you are a relatively new business trying to build awareness.
Online marketing is getting bigger all the time and its definitely worth having a small website, which is Optimised well for the Search Engines (SEO). You can show off your business here and give a customer some reassurance of your work standards by showing customer reviews and photos of completed work. If you can get onto page 1 of google in your local town then you should generate a good amount of small - medium size work. Facebook is another good source of advertising and it can be free to set up and you only have to pay for sponsored advertising. Facebookers love seeing photos, so if you are occasionally posting photos of your work and tagging people, it will almost work like word of mouth.
I would stay away from the paid directories such as yellow pages etc and never go with Yell.com or HIBU, those two are the worst marketing companies I have ever bothered with and will take your money and tie you in to a contract. If you want to pay for a website and have it Optimized (SEO), try and get it done by someone you know and who can also give you customer reviews etc.
One of the biggest things in my eyes, is how you Portray yourself to customers. If you are smart, polite, follow through on your promises and have the highest standards of work then you will always do well.