What you describe above is just a part of sales....it is not restricted to international trade. The fact is that not everyone who asks about your product will buy your product.

The best that you can do is try to identify the best prospects by looking at the information they give about themselves and the questions that they ask.

A customer that contacts you for the first time and does not identify their company, does not indicate that they understand your products, and just asks for complete price list of whatever product you may be selling is probably not the best lead.

A customer that identifies their company and/or has chosen specific products from your website and/or asks specific questions about those products is probably going to be a better lead.

The only other thing that you can do is to make sure that the information you send is clear, correct, and complete.

Far too often I receive incomplete information from factories which means that I then need to contact them again just to get the information that was missed last time. I am always impressed by factories that answer all possible questions in one email.