I'd skip the direct mail. I've seen pretty low returns in my fish business from mailings. What has worked well is craigslist postings. It's free. Also go hand out your mailer. Take the post card you were going to send out. Punch a hole in it with a hole punch and loop a rubber band through it. Now go knock on doors. If no one is home. Put it on the door handle.
Yes this will sound like an insane amount of work. It's gonna take forever to hand out 1000 post cards this way. Vs just sending them. But instead of 0.01 return rate. You'll be closer to 30%. People buy from people. So if you don't look like a neckbeard you should do fine.
Advertise where people look for the answers. For me I'd be googling. So perhaps you do some adwords on "spyware" etc on your local level. I'd be bribing best buy employees. Give them the first hour of wages or something for each customer that brings in your business card with their name written on the back etc. Then hit up staples, office max, etc.
Next up, call around and find out the prices to move into the nursing homes around you. Then ask to do a help session there some afternoon to the ones with the highest rents. You go in, and teach basic things. As a by product, you'll get help calls later and you know they have the income that can afford your services.
Next up, I'd figure out a way to advertise in the hotels that are the most business friendly. If a laptop goes down while on a business trip. They'll pay whatever is needed to get it back online asap.
Do you have a sandwich board up by the road pointing to your store? You'd be surprised at how much traffic that brings in. It does so much for my business that I put up a second one.
Your biggest returns will be on things that are labor intensive. Anything that is just put up some money to advertise you'll be beaten by larger companies. For instance in your newspaper. You might have a Best Buy or Staples add in there, a whole insert of 5 pages each. Both offering geek squad services. Vs your ad in the business listings section etc. The problem is, that customer who reads the paper has seen that service every week for the last 5 years. They will only look up your business listing in there when they have a problem. When they have a problem their brain already tells them to go to best buy. Thus your ad isn't being seen because the decision has been made before the problem exists.
You need to make sure your marketing reaches people in advance of them having a problem. Make it easy for them to know it's you they should call when they do have a problem down the road