The European union is example here, they wont export crude oil and energy product much, because they have lack of it and they need it by themself. This kinds of countries usually want to import energy products, from Russia example.

Regulations regulate different kinds of things related with specific goods and its import and export and volume, below are some most imortant.

• Import duties. One interesting thing here, what I have experienced, China is still now 100% focused to export. There are very high import duties for the most of the products what comes from the west, example for food products import duties are about 15–50%!!! meanwhile western countries have low import duties, about 0,5–7%.
  It proofs, that China is protecting its inner market and dont want westerners come and export to there, because money will go out from the country then
• import and export restrictions ( volume for certain type of product is limited)
• Different import duties for different exporters. Example in European union, if one country lets say France export something to Germany, then its not considered as import, there are no dutties and restrictions at all, but if Germany import from China, USA or some other third country, then there are duties and certain rules. China example prefers import from its neighbout countries likes Korea, Thai, Bangadesh etc
• concessions- Some countries give some preferences to some special countries. Example EU allow different African countries to export different kinds of goods to European union with zero duty. Its because they both win from this.
• time bounded restrictions. Example now Russia and EU have issues and EU not allow certain type of products to be imported from Russia for certain period of time and Russia does the same To EU.
• In regulations, there can be stated what are the requirements or specifictions, certificated , for different kinds of goods. If products dont meet the requirements, then they are illegal to import.

So, there are a lot of different regulations and You will find them from your country import or trade department or from Customs, there you will get al details. Just tell them what you want to import or export and from there and you will get all info you need.