Transportation:
Expedia-
I use Expedia for flights finding I do get the best deals many times plus I get Expedia points. Since I do fly one-way most of the time I just click on their calendar to see the cheapest dates. Once you select a day the price may change but a flexible date of one week show up at the top to reselect the your day.

Skyscanner-
Skyscanner search for low cost flights with many flexible search options. I’ve used Skyscanner a few times to find some airlines not showing up on Expedia and find better bargains. Local airlines not appearing on other search engines will appear here.

Rome2Rio-
Rome2Rio shows you a list of various ways and modes of transportation to get between two cities. Times are also listed as well as prices and companies.

Seat61-
Seat61 is a good detailed site for train travel.

Turo.com-
This site is like AirBnb except for cars. Turo consists of various hosts that rent out their cars. As with AirBnb there can be misrepresentations. (also see travel scams for Turo)

Other-
Uber is available in quite a few countries. Grab– like Uber in Asia. Ola– in India (also serves Australia, UK, New Zealand

BusMap: a very good real time interactive app for using the bus in Vietnam major cities and Bangok in Thailand. I used this quite successfully.

Navigation:
Maps.me-
This is an offline map which you pre-download when you have WiFi then you can use this to navigate with your phone GPS even when your offline. You’ll need to update the maps occasionally after awhile but you’ll probably have moved on by then. With Maps.me you get way more details with small streets, alleys, and trails than Google Maps. In places like Goreme Turkey, Marrakech/Tangier in Morocco I found them indispensable for the old market areas, every alleyway was shown.

Altas Obscura-
Atlas Obscura is a website of off the beaten path and unusual things to see across the world with maps, descriptions and pictures. You can even add new places you have discovered.
If you get the app you can pin places you have seen.

Accommodation:
Expedia-
Expedia is good for searching hotels and other accommodations. Hostels are now appearing on Expedia but not all. Occasionally I find the same hostel I found on Hostelworld for less plus get points. I have tried so many different search site but keep coming back to Expedia for finding the best price about 80% of the time. I like that Expedia shows you the complete costs upfront.

AirBnb-
I will use AirBnb occasionally if I plan on staying in one place for 28+ days. Many hosts offer 10 to even 75% off for long term stays which come out cheaper than hostels. One drawback is that you are alone. But if your feeling like some alone time this works. You can still meet other people traveling at famous sites.
There are many filters to apply when searching for a place and it will show a map of the locations available for your search filters. Try and book with a Superhost to avoid issues, there is a specific filter for Superhosts. If you zoom in, the map will show a circled area for the approx location of the place. (Also see Travel scams). I will look at the picture posted for the Airbnb

Couchsurfing-
I was introduced to Couchsurfing by another hostel traveler. These are simple accommodations e.g. sleeping on someone’s couch. I have signed up for an account but have not used it yet. This would be useful for finding a place to stay short-term if everything else is booked, need an emergency overnight, or on a really tight budget. The site asks for $60 deposit up front to show that you are a serious booker and requires a reference first.

Hostelworld-

I use this Hostelworld extensively to book hostel which keeps track of my bookings on a nice list. They have extensive pictures of each hostel. They have a nice search function with filter. Check the full pricing and read the hostel information for any extra charges for any of the amenities or daily use fee. After finding a good hostel on the website you can check the hostel’s specific website to see if there’s a better deal. Sometime the hostel’s website can show more information such as

Insurance:
World Nomads-
After an internet search I came across World Nomads as highly recommended with good claim response and endorsed by lonely planet. I’ve been using World Nomads consistently, however I’ve not had the need to use it and test them out for claims. I have seen a few bad reviews here and there but I have found nothing insurance-wise that didn’t have a few bad reviews.

Tours:
Viator-
Just enter your destination into Viator and it will come up with a list of top and popular tours available. You can set dates, duration and price limits. I’ve used Viator a few times before with success. You can also get an idea of what to do in your destination then seek out local tours to book. Hint: check under the ‘Additional Info” section to see the actual tour company. Then go visit their site.

GetYourGuide-
Has a similar function to Viator. I have used Get Your Guide on occasion as well with success and smooth operation.

Website to search for private local guides:
Tours by Locals, Rent a Friend,

Imaginative Traveller or Intrepid–

I don’t particularly like traveling with group tours, not because of the people but because the itinerary is tight, fast moving, restrictive and costly. However, I have used Imaginative Traveller on past trips because their pricing and itineraries for budget travel are good. You also meet like-minded people on these low budget tours.

Visas-
iVisa.com is a good online website to pre-arrange visas. Though they do have a significant charge to secure your visa. Recently I noticed they had a significant charge for a tourist card for Mexico which you could obtain for free at the Mexico consulate website for free, or just get the card on the Airplane. But they do provide you with information on what’s needed to enter a country and you keep all you info/visas in one place. So use this site sparingly.

Travel scams
Overpricing- I have been overcharged for some side tours as I found out later. Since I’m from the U.S. I keep using my U.S. pricing standards of what seems like a good deal when in fact you can be charged double or more of the local standard pricing.

Buying souvenirs-
In many countries the first quoted price is way too high, counter offers and haggling is expected so the price starts off high. This buying process can be a social event with tea or other items are offered while you look around the store. Chit-chat is part of the process as well. After all the cordiality you feel guilty walking out without buying anything so you end up buying something.

At some point you need to just stop buying souvenirs on impulse. You’ll be very tempted but try and buy more practical useful items if need be. After awhile you will end up tossing most of the impulse souvenirs you bought when you move or your home becomes to cluttered.

When I get hassled to buy stuff on the street I say I have no room in my bag. Their quick comeback will be that they can ship it to my home. My quick comeback now is that I have no home.

The street conversation-
Often a stranger will approach you for some conversation, they can be quite forward and pushy. They will ask if you need directions to a good restaurant or something else. Then route you to that restaurant which will be owned by friend or most likely a relative of theirs, which may not be bad but they inevitably route you to a relative’s shop first and hold you captive for awhile.

With these light scams you need to be quite assertive without being rude, extend your goodbye’s and walk out. Do not feel guilty! You may not feel too bad about spending the money or buying something at the time but all this adds up when your doing long term travel.

While I was in Morocco I would get many people offering to be my ‘guide’. I already knew where I was going (via maps.me) but I would get these guys that were very insistent on following me and ‘re-directing’ me saying that was not the way. I would ask them if they even knew where I was going? Sometimes they offer a good bargain shopping experience. I make it quite clear that I’m traveling light and absolutely will not buy anything. I’ve had some respond “how about we just talk?” I’ll say sure no problem I love to talk if you have the time, but be assured that I’m not going to buy anything. Sometimes I would converse with them for awhile and ask questions about them.. This may perpetuate the problem but after some good conversational exchange I will donate something like you would do with street entertainers.
Other traveler websites-

Nomadic Matt is a website that I enjoy. He has extensive travel and offers a lot of insights on travel scams.