I have fixed PCs for a living. I was very efficient at it too. Get a shop that is highly visible, near a train station or in a busy area. Make sure parking is available out the front for at least a few cars. Don't get anything upstairs. Get lots of signs to plant in a circle (a half to one kilometre away from the shop) around the shop indicating where you are. That is your 'catchment' area.

Be FAST with the repairs (some things need overnight checking) but make the repairs in 1 to 12 hours max.

Be RELIABLE with the repairs. Offer a guarantee too. 3 months is typical.

If you are a one man band then you are stuck with having to close the shop while you are out. That means customers can't 'carry-in' the repairs while you are away, so try to find someone to accept carry-in jobs while you are out at offices and homes.

Get a good stock of spares, don't be running out for things. Sell things too from your shop.

Ask for CASH for all jobs. You are not sending invoices if you do and you can do a lot more with CASH.

Estimate how many chargeable jobs you can do in a day, multiply this by your hourly rate ($100?) and that will be your daily takings. Get a spreadsheet and work out all your costs and find what you'll make in a day.

It's always better to start a repair shop with TWO technicians. Do this if you can.

Be choosy about what you do. You can't do EVERYTHING, so just pick what makes money and what doesn't.

Be careful about the shop's security. At times you'll have dozens of computers worth (?) let's say $10,000 laying around, plus all your spares and items you sell, so get insurance and make the place like a fort.

Work like a Trojan for the first year. You'll need to do about 100 hours a week to get established.

NAIL ALL competitors in your area. I wrote the book on DIRTY TRICKS and drove all my competitors OUT of business. Do the same.

Tie up business clients with contracts if you can. Tell them they get priority if they sign up. Every business has a dozen or more computers. Every home has maybe two. So go after the business clients.

Do a leaflet drop to all the businesses that don't have thier own PC people to do repairs. Monitor the success of the leaflet drop and do it again periodically.

I used to drink beer at the pub with lots of my customers. This cements their business in place because they get to know you and like you. If you don't drink beer then find another socialising way to connect to them. It really pays to be very friendly with the customers and get to know them.

Ocassionally give them little 'gifts' of a free service, free parts (where they are cheap), free advice. They like it but let them know you are doing it otherwise they don't appreciate it.

Get your car REALLY NICELY painted with a quality sign advertising your business. Keep the car clean.

When it comes time to hire employees, don't ever believe that paying more money gets better people.

There are other services you can offer too. I have explored this angle intensively and there is a good money making service that you can offer businesses that pays even better than do repairs and support. $250 per hour at least.