I set up a new campaign for each area that i target and use separate keywords for each area, although realistically each set of keywords is the same but tailored to that area, also i make all my keywords exact match only, o.k it will cut down on traffic but it will stop a lot of related searches click through to you, so for example your keyword is anytown carpet cleaning if you just left it for broad match then your advert would show up if someone was looking for anytown, carpet or cleaning on their own but by adding exact match by using [ ] only some looking for the exact match [anytown carpet cleaning] would see your advert. I probably have around 20 keywords for each campaign all based around obvious search words and location.