How to escape criminal
The saddest cases which happen to the tourists abroad are connected with criminal (whatever a victim or a committer a tourist is). Usually, the tourists are not aware about the local laws, but the foreigners are under local jurisdiction. So, the things which are considered to be normal in your native country could be very hard cases abroad. It is very useful to read about some cases at the internet or consult the professionals. So, the most popular sentences abroad are connected with the drugs, firearms, antiques and jewelry or photography. Usually people do not know what medicines it is allowed to take, that is why the medicines which are considered to be normal in your native country turn to be illegal in the foreign country, especially tranquilizers and amphetamines. Also you are to be careful with quantities which expected to be used for the personal needs, but the local authorities suspect that you purchase these medicines for the commercial purposes.
Another issue is firearms. Even if you have the official permission in your native country, you have to register your firearm in the strange country or just purchase the official permission right at the airport. Everything depends on the definite country. In some countries it is forbidden to own the firearms up to thirty years old, unlike other countries.
As for the souvenirs, the first thing you have to check is if it is authentic or national treasure. So, surely, the official shops do not have the national treasures for sell. The black market could propose something similar, but make sure that you possess the documents which define this souvenir as the reproduction, even if you have to ask the national museum to help you. The photos of the important social objects like the railway stations, government buildings and similar are forbidden as well.
If you are not sure in some issues, ask somebody at the embassy or consulate before your departure to avoid the troubles later.