What do you need to take care of so as not to be returned from the border:
1. Have a document from the event you are attending (conference/training invitation, festival ticket purchased online, hotel reservation, letter of invitation from a friend).
2. Have a travel insurance that covers your stay abroad.
3. Have a return travel ticket.
4. Have money in cash or better a bank account statement saying that you have at least 60-70 euro per day for each day of stay.