The earthquake causing all cities to fall means they at least lose their main infrastructures, electricity, water, and major roads will be blocked, although not all buildings will be earthquake flat because the denominations survive in Rev. 17:5 until the faithful leave them in Rev. 18:4 to obey Jesus directly.
The alternative to preparing to survive is mostly suffering and death. It is sad most prepper groups ignore this Revelation prophecy, which is the one disaster most likely to occur, in spite of their many fears. Never the less, it is wise to prepare well to survive, especially if you find out you were left behind after the pre-tribulation ascension or rapture.
Some prepper groups may be helpful, others will not be. For example, if you have Diabetes, you will need lots of meat so look at what long term food plans offer - if it's mostly Carbohydrates you may end up mostly dead. Another factor is price. You might not be able to afford a company's meals for 3.5 years or more so you might need to build your own freeze dryer as shown on YouTube and freeze dry all your own food. Be sure to test your product to make sure it rehydrates and cooks well.
Medicine will be a major problem if you can't get what you need to survive. You will have to research your own needs to determine if you can live without some medicines, substitute some foods and exercise, or if you can make a small medicine production machine so you will be able to live.
Leaving fallen cities may be difficult by ground vehicle when the roads are down so you might consider building your own human size quad copter. Apparently a Chinese firm makes these but a home made one might help you escape to a forest, desert, or other location. You may need to prepare a refrigeration device that can extract pure water from the air and filters that can turn urine into dirnkable water.
Power is another factor. You must accurately asses your needs and supply them. There aren't many home power production systems that work and some that use water are not legal in overly regulated areas. However the major world wide disaster will greatly slow down regulation enforcers, as many will be recruited to stop violent crimes by people trying to survive by stealing from others. That is what you get for not teaching EVERY child Jesus' Gospel in public schools.
Emergency communication by Ham Radio requires a license, so go to a ham club, attend lessons, take the test, and buy a ham radio. Cell phones and Internet may be on in some areas and off in others. About the only way to be sure of getting reliable access is a system that depends more on balloons or satellites than on towers and land lines. It is quite easy to live without communication unless you think you could have an emergency or need to see if a route is repaired before traveling.
Education material for your children may be needed. However American History has many great men that were educated primarily with a Bible, such as Abraham Lincoln. Stock a variety of Bibles, from pocket size to giant print so you and your family can read it wherever they are and see the letters without a magnifier. An audio Bible may be a good choice.
The problem of praying seriously enough to get God's help might be solved by some people, we can hope.