Hi Ikbar , You need to identify your market , I mean the geographical distribution of your market , not all product are acceptable in the whole market , so as a first step choose the countries that your product has high market share in it. Then you will need to determine your customers (which in your case will be companies as your case represents B2B marketing).
The internet as a whole & the social media in specific can give you a primary access to those companies .
Finally, if you find some countries in which your product has significant market share & you already prepared a list for some of expected important from those countries, I would recommend you to visit those countries in person & judge those importers in the real & take this visit as an opportunity to search for more importers from the real field.
This solely depends on the product you are trying to offer. Mass market products and specialized market product differ in approach.
And the right formula how to keep clients forever has not been invented yet. Quality and fast market response is your best bet.
In My opinion,Reach at your customers with the help of social media,emails,marketing etc.