Have the Expertise
Having the expertise is the first requirement for any business. You should know about trucks and how to repair them. If you do not have the expertise yourself, you will need someone that is trustworthy and has been in the field for some time that can handle the pressure of work. Do learn about trucks yourself in the meantime so that you can handle things on your own as well.
You will need a decent bit of investment to get the business running. In case you do not have the money, make sure that you can get a loan from a financial institution. Make a feasibility and know that how much you will need to set up the shop and how much you will need initially for your operating costs.
Get Resources in Place
These will include both material as well as human resources. You will need the right sized shop and the right infrastructure to cater to the needs of the trucks. You will also need all the right tools to do the repair work. Having trained and experienced personnel will help you in getting the job done right every time and you will have happy customers.
Make sure that you get all the required licenses from the authorities. This is important as without licenses, you will not be allowed to operate. Make sure that everything is done as per the rules so that there is no problem in getting licenses once you apply.
The best places to promote your shop are the places that are frequented by drivers. Post ads or give special offers and they will give you a try. If you do your job well, you will get more business as word of mouth about your good work will spread.