I would advise against it. I've placed 2 adverts and found it a complete waste of time.
Who reads the local paper these days? And of those people who'll be looking for your service right now?
I now advertise with google and have Adwords set up with them. I just don't think you can beat it. That person is already in buying mode looking for your service.
Pound for pound you'll get a much better return.
Why don't you ask your clients if they read the local paper? Gauge how much of your target audience read the paper.
If you do decide to run an Adwords campaign, use the google keyword tool to see how many people a month are looking for your services, and also to see what keywords you should use.