One of the best ways to prepare for culture shock from moving overseas is to visit your new residence and country before your move if you can. Visiting a new country can be difficult depending on your circumstances, but experiencing a new culture first-hand will go a long way to preparing you and make adjusting to that culture easier. If you know where your new residence will be, visit that area and spend some time getting to know the streets and the locations of nearby services, stores, and facilities. You could even do a test run from your residence to work and take pictures and notes for future reference.
Online research is another useful way to adjust to a new culture. Maps are always helpful, and blogs by people who live in the area can be valuable resources. Forums of expats or native residents can also help you learn about the local culture and prepare you for the move. Also, spend time learning local laws and customs, including table etiquette, formal and informal dress codes, greeting gestures, and more.
If you are moving to a country that predominantly speaks a language other than English, learning the new language will help ease you into your new residence and lessen culture shock when moving overseas. Communicating with the new people you will live with will help you better navigate your new host country. Consider carrying a pocket-sized dictionary in the new language around with you. For countries where English is the most-spoken language, local slang or colloquialisms might cause some minor culture shock, so take some time to learn those, too.
Moving overseas is challenging, and you may encounter situations where you will have trouble knowing what to do. For example, certain media outlets or foods you are highly familiar with now may be unavailable in certain countries. Reducing culture shock is all about learning, and you can learn plenty of new things even after you have done all of your research before your move. The adjustment stage will take time, so have an open mind, be open to new experiences, and you will feel more comfortable.