First of all, I do not intend to drag anybody through the way I find and book flights and reservations. Times and methods change. Now there are hundreds of mobile phone apps and websites available for ticket sales and hotel or event services and reservations. Shoot, when I traveled over seas the first time, I booked a ticket to India by using a booking agent connected to the ISKCON Vaisnava temples USA and received a plane ticket on Pan Am airlines. They do not even exist anymore. 🙃... So, as far as finding good deals on air flights and hotel reservations, I generally just wait for them to be advertised on sites like HotelTonight and Booking.com which has been very helpful for me. My favorite sites are HotelTonight, TripAdvisor, Get Your Guide, Google Maps, Booking.com, TripScout, and Delta Airlines website (because I am connected with their frequent flyer sky miles program and they are a good airline). Get Your Guide website also announces good deals during certain times of the year. On my cell phone, I have the apps for each of the websites mentioned above and a combination of these will carry me through the planning of every itinerary. Oh, and it is good to follow a few professional travel bloggers on Instagram and Pinterest. Both of these sites provide lots of eye candy with plenty of information. I also watch YouTube videos about transportation options in the cities I travel to.
Many cities have wonderful sites that are really useful for booking and purchasing tickets for events, transportation, and reservations in the region of the city. One of the sites I have in my travel bookmarks folder is the Paris, France Tourist and Convention website that has a clear, easily navigable list of events and sites that everyone can use to choose, research, reserve, and pay for right there on the website. There are even several price ranges included for many sites that we can choose from. What the tickets include and the prices are made clear and payment options are also straight forward. I always buy the Paris PassLib' package which includes all transportation fares (besides taxis), free entry to some 60 museums, discounts for many other places and events, and a free ride on the Hop On Hop Off bus for one day and a free ride on the Paris Bateaux which is an hour on a tour boat up and down the Seine River. We are also able to reserve a "time slot" for the Louvre Museum through the PARiS Convention and Visitors Bureau website. This is going to be a necessary requirment going into the future for Louvre Museum entry.
I have also bookmarked the Copenhagen, Danmark tourism website because it is also very useful for booking and paying for the same kind of reservations and packages we receive with the Paris PassLib' package. Paris and Copenhagen are both cities we will be visiting often in the future. This is why it is helpful for me to have their websites in my travel bookmarks folder. Many cities will have their websites that can be very useful for visitors. City maps, including metro, train, and bus lines are also included with these city card/pass packages.
When I brought my plane ticket to India, it was for my very first overseas trip. I called the booking agent via landline phone because there were no mobile phones then. The booking agent was referred to me by the temple president of ISKCON Denver, Colorado. I called, told him when I wanted to go, and where I wanted to go, and he took care of everything else for me. You can go to my page, "India " if you want to read about the trip.