Not all typhoons are powerful, but they are the most violent weather event on Earth and can be deadly. These steps are not equally important, I included as much information as I could.
Consider where you are staying. Are you in a small house / one-story building? Are there many windows in your room? How far are you from a river or the beach? Are you in a relatively flat neighborhood or on a slope? Are there many trees near you?
The safest place is far from rivers, canals and beaches (waves can rise several meters during the storm), away from cliffs and mountain slopes and anything that can fly or fall over the house, so preferably in a building High (large hotels have backup generators that are doubly useful) and not at the bottom of a slope. If not, on an elevated floor.
Check house drains and make sure there are no obstructions. Remove pots or anything near windows that can pass through them. Paste a large X into the windows to reduce breakage.
If you don't speak the local language, is there anyone (whether invited, host or personal) who can help you with the communication?
Depending on how risky your location is, look for the location of the nearest shelter. Ideally, you should move there before it gets worse. No one wants to drag their things outside during a violent storm, perhaps at night, trying to find a place in an unknown city.
If you are planning to drive, keep in mind that cars can float under heavy rains. If you plan to train or fly away from the risk area, do so in advance because flights / ferries will be canceled before things get really bad and subways and train tracks can flood.
Typically, typhoons last approximately one or two days. Get some food for the time you will be inside, especially water in case the supply is interrupted.
If you need a daily medication, think about stocking for more than a couple of days, in case you are trapped.
Flashlights and batteries are also useful in case of a power outage.
Communication is very important, so a battery powered radio is also good, although you can also get a portable battery charger and use the Internet from your phone. Keep your phone charged. Know some local emergency numbers.
Have a small bag of essential items ready in case you have to evacuate. This will happen quickly, you will not have time to find your things or pack a bag.
Obvious, but stay inside. Risks during the typhoon include being dragged by the winds, collision with debris dragged by the wind, flash floods and landslides.
Watch for the speed with which water accumulates outside. Water can rise very fast, so you want to have the least surprise possible.
Stay informed. Watch or listen to local news, look for alerts on how the situation is changing.
Keep someone in touch with your location. I think Facebook has the "I'm sure" function in case of natural disasters. Google Maps has a "Share location" feature where you can send someone your exact location in real time for a certain period of time.
Most importantly, if local officials issue an evacuation order, evacuate!
Even after the storm breaks, there is some risk. The rivers will still be full or flooded, so stay away from the banks. The ground will still be full of water, so stay away from the slopes of mountains, hills or any place where the ground is loose.
Some debris or branches that were trapped above and out of sight may still fall suddenly.
If you can, avoid walking in stagnant waters, as they can transmit waterborne diseases.
Consider volunteering to help with recovery and cleaning. The elderly generally resist evacuation because they find it difficult to move, so it is useful to check if someone is trapped in a flooded house and alert local teams about them.
This answer is based on a personal experience, so these resources are specific to Japan, feel free to edit and add others.
Japan Meteorological Agency
Joint Typhoon Warning Center
JR East service status
Twitter safe trip to Japan (mainly English, but also Korean and Chinese)
Japan Shelter Guide, iOS and Android application
Pocket Shelter application
Application of safety tips
Tokyo disaster preparedness
Shinjuku municipal website This is a neighborhood in Tokyo, I am sure that other places have their own sites. This is a machine translation, it is also available in Thai, Korean, Chinese, French, Tagalog and Spanish, among others. It also presents a map of shelters in the room.
NHK News (English)