Beyond insurance, in the US, you need to have sales tax licenses for your state, county and city.
Make sure that you properly collect and submit sales tax paperwork and receipts to the proper government authorities.
Most states are VERY diligent and relentless in tracking down lost sales tax revenue.
Make sure that you are properly filing quarterly tax paperwork with state and federal offices too.
Check for competition, and what they charge for services that you plan to offer.
Honestly determine if you can make money at the prices they charge.
In the US, the number one reason that small businesses go out of business is that they do not understand their market and do not plan enough of a line of credit (or cash) to run for the first 3 years.
After looking into the legal aspects of starting a small business, create a business plan and budget.
Assume that you will need to pay all of your personal bills and living expenses for the first 3 years that you are in business from savings or income other than the business.
Next comes getting a source of parts and supplies at wholesale. You need a supplier that can deliver parts quickly so that you don't need to keep too much inventory on hand.
PC parts depreciate faster than day old bread.
Of course, you need a good set of PC skills. Both hardware and software.
Informal "networking" can be critical to your success. If you have a large social circle, it is much easier to get the word out that there is a new place to get PC repairs done right.
Not to be negative, but in the US, I see PC repair going the way of appliance repair. PCs have become cheap and basically a commodity item. Many people replace a dead PC rather than repairing it.
To be successful, you will need to find a niche,
Data recovery
Data transfer
Home network setup
PC security
are all market segments that have good potential for growth.
Chas