When you are running a job as computer repair and upgrade, it is recommended that you avoid mixing hardware apples and software oranges. Your clients should have support agreements with the providers of their software or with a consultant. When you are called in to make a repair, your first diagnosis should be to determine whether you are dealing with a corruption of the software, an improper setting for the application, a problem with the operating system, or a failure of the hardware. You should be able to make basic adjustments to the operating system, but be very careful about offering to make fixes to application software unless you are fully capable of doing so.
You should build up a library of technical reference books about PCs and their components in accordance with the up-front expenses. There is a great deal of information available on the Internet from support groups and from manufacturers. You’ll need a basic tool kit, including screwdrivers of various sizes. Other valuable tools include a simple voltage tester and an antistatic strap.
In other side, for the cost or charge of the service, you can give a charge by the hour for your time, plus the cost of any parts you install. As a professional, you should be able to buy components at discounted or wholesale prices and resell them to your clients at a marked-up retail rate. For regular customers you might offer to sell a block of hours at a discounted rate. You can add a premium to your rates for after-hours and weekend work.