First contact the end user (customers etc.) and ask them to suggest companies they want to buy from. If you are a small company it is easier to work with a small distributor. Note, however, that larger multinationals such as car manufacturers have lists of preferred suppliers. If you want to sell to them, you have to a pre-approved supplier.
In our book “Export & Import – Winning in the Global Marketplace” ISBN 978-0-9681148-1-0 these topics are covered in depth