You must go through customs control when crossing a state border, both when exiting one country and entering another.
Choose the right corridor. There are usually two corridors at customs: red and green. If you have items to declare, or you want to declare them voluntarily, head to the red corridor. If you have nothing to declare, go through the green corridor. By choosing green, you automatically confirm that you don't have any goods requiring mandatory declaration. Keep in mind that this may be checked.
Take only what's necessary. Personal belongings within reasonable limits won't raise questions at customs in any country. You can legally bring in a suitcase with clothes, a smartphone, a tablet, sports equipment, or musical instruments. The main thing is that all of this should be for personal use. For example, one new phone won't cause problems, but for a second new phone, you might be asked to pay duty.
Declare valuable items in advance. If you're taking expensive items with you, declare them both when leaving Russia and when entering another country. This will protect you from possible problems when returning, as customs officers may assume you purchased them abroad and demand payment of duty.
Check medications before traveling. Take as much medication as you need for the duration of your trip. Although in practice prescriptions are rarely asked for, theoretically they may be required at customs. If medications contain psychotropic, narcotic, or potent substances, be sure to take a prescription or doctor's note confirming the prescription. Some medications may require special import permits. Keep in mind that lists of controlled substances and their import rules differ in different countries, so even common medications and dietary supplements may attract interest from customs officers.
Learn about restrictions in advance. Importing and exporting works of art, antiques, weapons, plants, and animals often require additional documents and permits. Some items, such as certain types of weapons, medications, or counterfeit brands, are completely prohibited from crossing the border. Before your trip, be sure to familiarize yourself with the official lists of allowed and prohibited items for the country you're traveling to.