I'd say 90% of travel prep is thinking what you need to carry with you, what are the essentials you need?
carry on you:

passport, visa, cash, debit card, phone,
sunglasses, hat, *decoy wallet

weather adapted clothes

apps : local transport app(taxis and such), debit card app, airline app(or ship cruise app)
itinerary notes (how to get from the airport to your airBnB/hotel/capsul hotel/hostel)

backpack :
clothes, jammies, money, tissue,
*offline translator device, electricity adaptor
, eye wipes, band aids, compass.

info (backpack and phone):
travel insurance, friend contact, embassy, emergency numbers, (city and transport information).
documents copies(e-tickets, passport)

info to keep online and with your contact:
documents copies(e-tickets, passports, itinirary, hotel information, travel insurance policy)

your main expenses:

travel organised(group) tour/package/airbnb, itinirary
communication package for abroad or local sim card abroad

problem shooting:

if you lose your passport abroad :
1.if you think you will miss your flight Report the problem to your airline.
2.1.remember the document you copied? they will help you in the following :
Report to the police and get a police report.
2.2.if your money was stolen you could ask a friend to wire you via western union
(in the post office). you might need about 60$ for the embassy to reissue you a temporary
passport and stuff.
3.Visit your country's embassy or consulate and get help (a new or temporary passport to
return to your country).

visa :
the visa is a recommendation made by the consulate to the immigration office and gives the
specific status of work ,residence, travel etc.
a visa, which is issued, by the embassy or consulate, of the destenation country (in
the traveler's country) shown with a passport quarentees the recipient entry to the
country for a set amount of time. some countries have bilateral agreements, so that
they do not require a visa to be issued for travel and to stay there for a set amount
of time without a visa.

flight :

the flight ticket is purchased from an airline company (in the airport or via
a website or a branch store) or via a travel agency. nowadays you have your
passport function as a ticket.

some destinations require 2 flights, the 2nd flight is called a flight connection.
you want to leave plenty of time between the flights (4 - 6h and pay attention to
time differences) and the flight connection(if are), and book the return flights
with the onward flights at any case.

as I understand : Airlines, generally don't assume responsibility for missed
connections on two separate airline company tickets.

if you missed the flight connection through no fault of your own, the airline should
rebook you on the next flight, which, if it takes off much later, you may be compensated
for meals or accommodations, unless the delay was caused by weather (in this case you
might not be companseted for meals or accommodations, only for the flight).

if you missed your flight and lost your money, the flight company can loan you for a flight

check in : this is the acquiring of a boarding pass from the airline, which is the
permission to board the airplane for a particular flight, it identifies the passenger
, departure time, and flight number.
__option A : buy the ticket online (this is called an e-ticket) then check in online
and print the boarding pass or have it sent to your email or smart phone as an SMS
(some screen capture the pass and display the picture with the smart phone as the
boarding pass). there are also apps that do this and display the boarding pass.

__option B : buy a paper airline ticket, you will get your boarding pass in the airport
when you enter your airline's check in from a clerk or print it from a self service kiosk
at the airport, and the 2 documents will be required to be attached.
boarding passes are issued about 24 hours before theire flight.

Baggage Claim : you take very small baggage with you the rest you leave at check in and
collect it after each flight. if you can not find your luggage wait then report it in the
check in.

flying stand by : if you have want to change to an earlyer flight : in the check in
request stand by, then if seats are available