maxwell00, Welcome to BC Forums!
For starters, you could place an ad in your local newspaper, maybe at first offering the first 25 customers a 10% discount. You should research pricing in your area for these services, as these will vary from region to region, as well as home & business. Give a discount, but don't be afraid to charge, as much of this can be time consuming, as I take it you know. Give these first businesses a couple of cards to pass to others & for a 10% discount for referrals. Word of mouth advertising is the very best that you can have, provided you do quality work.
On the other hand, it will doubly count against you should you do sloppy or incomplete work, so make it a goal, your Customer is #1. Make them happy with the work that you perform. Let them know that if they're not satisfied, neither are you. Note that there will be a few that you cannot satisfy, once your business grows, you can then pick & choose.
Make business cards & ask local businesses, such as office supply stores, anywhere that offices obtains their supplies, including printing needs, to place a few of these in a prominent place, such as near the check out area. Any cards displayed or handed out, write a unique code on, so you know whom to thank. Scatter a few signs where allowed, but no tacky stuff with magic markers. Do the same in public libraries where allowed.
Consider creating a Linked In profile & every time you do a job, keep contact information, ask later to join the circle, you need exposure any legit way you can get it.
Also consider at first, until you get a good line of business customers, to also include home users. Many IT pros has a blend of business & home customers, this really makes for good advertising. There are way too many home customers that has poor security in place, router & software. Ask to use these as references & be sure to give them cards also, give them an incentive to sell your service for you by say, if one gives you 3 referrals that leads to a job, give that person a little bonus, such as a free checkup (which can lead to another sale).
Be assertive, but not aggressive. Speak to customers respectfully, in a manner that they can understand & avoid slang, as well as political conversations. Some customers will be chatty, listen but don't offer an opinion over silly stuff. If you plan on being a professional, carry yourself as one. Customers will have respect for you by doing so & will see you as someone who knows how to knows how to treat them, as well as trust in you. Don't do anything to compromise that in your dealings.
Until 2006, I was a Regional Sales Manager myself, so I do know about selling services. I've won & lost sales, though most of my losses were my earlier years.
Maybe some others has ideas & will chime in.
Should you require further assistance, we're here 24/7. Ask anytime.
Good Luck with your new business & hope that it's a successful one.