For better or for worse your phone quite often becomes your most useful item from home and some of the time your best friend.
If you have decided to take your smartphone rather than digging out your almost legendary Nokia 3310 or your prized Razr from under your childhood bed then you will be using your phone a lot, regardless of how free and spirited and authentic you want your experience. You have to remember that the countries you're more than likely to be travelling probably have better wifi than than the UK and are not still in the Victorian times. If you want an authentic and easy experience take your phone and look after it the same way you would at home. You're just as likely to get your phone nicked in London as you're in Vietnam.
If you're worried of breaking your phone then remember you are as likely to drop it after a few too many breezers at home as you are on a moped. If you're still worried get a case that is actually going to protect it. I bought an otter case for mine. While my phone is now twice the size it is now almost indestructible. They are expensive but considering mine has fallen from a moving moped and survived I think it is worth it. If the fear of thieves and bandits is still strong, then grab a hyper fashionable (in China) lanyard and get it attached too. With all your new accessories you're ready to roll/ swipe right.
However, if you want to make sure you're using your phone for more than just swiping right and pretending to talk to people on Facebook so you don't have to speak to that annoyingly friendly guy next to you then make sure you have some good apps that will be useful when travelling.
Here are a few of the apps that have both saved me a load of money and have also actually been useful to me.
Either Maps.me or Google maps
These have both been a lifesaver and money saver more than once. Maps.me is a free app that you can download whole countries onto for use offline. With the maps downloaded offline you can keep GPS on without spending any roaming fees, meaning you can walk/cycle/ drive around everywhere knowing where you are and more importantly where everything else is. No longer can taxi drivers ask you for extortionate amounts claiming the distance is 40km when actually it is only 2km. With the maps downloaded you can plan your route around towns and any of the sites.
I only include Google as well, due to the incorporation with Google search. On Google you can also download whole areas to your phone. A lot of times I have searched for a restaurant I have heard of on maps.me to find it not included on their map. However, bring up Google and there it is. Sometimes a combination of both is perfect. However, why not just Google then? Well for example in Nepal you're unable to download maps offline, and also maps.me does actually work better on the most part.
Xe currency app
Moving between countries and their currencies can leave you stuck trying to do long multiplication for the first time ever. Even the best of us can have troubles, especially when also trying to convert between dollars and pounds on top of any other currency. This app let's you add any currency and type in any amount (in their calculator) and it comes up with all the different amounts. Once you log back onto the internet it will automatically find the newest rates for use offline later. Next time someone gives you a price in dollars and then some other figure you can see how truthful they are being. This is especially useful in the post Brexit, Trump asshole of a world we live in where western money just doesn't mean that much anymore.
Hostel World/Hostel Bookers/Booking.com
All of these are great for finding your hotel and seeing reviews from others and how much they cost. However, only booking.com will let you book without taking a booking fee. While this isn't huge it is still annoying having to pay 15% extra just to book a room. I recommend using the others for reference and then either contacting them directly or using booking.com to do the booking.
While WhatsApp now lets you call everyone on your contacts for free on Wi-Fi, sometimes you need to call a number of someone you've never contacted before. While a lot of people get sim cards when you arrive, if you're only there a week or two it's not really worth it. If you get Skype you can buy credit and call any number using wifi. The amount of credit used is about 1p per minute, so 10 quid will last you 12 months. That said it does not work in India. So get a cheap sim in India.
Your photos are pretty much your most important souvenirs from travel. Losing them would be the worst thing ever. Of course there are lots of cloud based apps, but I've found Google Photos to work really well. You can also hook multiple phones up to the same account. The app uploads the photos automatically and will ask if you want to delete them off your phone once it's done uploading. You can either buy storage or upload unlimited photos at just under full resolution.
Another inconvenience when going outside of your own country is that using your card means being charged exchange rates. While you can bring cash with you from home, carrying such large amounts with you is also a terrifying prospect. The best alternative I have found is Revolut. You sign up via their site and get a card sent to you within a week. Then you top up the card with either dollars, euros or pounds and you can use it anywhere in in the world. Revolut use the current exchange rate and don't charge any commission. The only downside is you can only top it up with £700 per year unless you pay for their premium account. However, considering the card also counts as a credit card meaning you can book flights on sites that only do take credit card, it's a pretty good idea to get one.
While all of the apps above are incredibly useful you do also need to remember that a lot of travelling is spent travelling. To while away the long hours on buses having a phone full of games, books, and films is the best option.
Netflix and Amazon Prime
Both do require you to have an account, but both now feature the option to download things offline meaning you can fill your phone with Mean Girls, Chef's Table and all other things.
There are hundreds of other apps for books and games so I probably won't go into all the ones I use. Although I highly recommend Dots and Bloons.
This is also a small bit of self promotion. Over the last few months the most useful tips of where to go and what to see have come from fellow travellers. Trying to write down everything is a bit of an effort and my note taking is awful, so I created a Facebook group where you can upload your best places, secret ways into places, best munch spots or best travel options. No one wants to have an awful time so why not share your chosen places with other similar people. You can upload a place with the location meaning other people can search for them quickly.