Manage credit cards and money
I travel with 2 credit cards, one is a Master Card World Elite and the other a Visa Gold. They provide me all the insurances I may need and prevent me from spending extra money on that. One of them will either get expired, lost, stolen, broken or unusable. I make sure each card have an expire date that is not too close from each other. There's no purpose having 2 cards expiring the same month.
I have a trusted parent who can collect my mail. That's useful for bank, company and paperwork. He emails me important thing using a scanning app on the phone.
I save every administrative document in a secured server that I can access from anywhere.
Phone and SIM cards
I have an Android phone with 2 sim card slots. An Android phone often has a better battery autonomy than an iPhone, have in interchangeable battery and benefits from all the advantages from a smartphone.
I chose a Macbook Air 13". That's light, resistant and lasts for real for 6~10 hours without charging.
However I strongly advice to charge and remain plugged as much as possible. You don't want to think « I should have charged when I was in... »
Storing personal data
All my paperwork, passport, driving license, diplomas,... are scanned and stored on a secured private server. My work is mostly on Github and my paperwork on that server.
For travelers who don't have a technical option to have a NextCloud on a Raspberry Pi or other private cloud service choosing Mega or Hubic may be good alternatives. They are better than Dropbox as you have much more space for free and data is not stored in the U.S.
I carry around 35L of luggage in 3 different bags: the main backpack, the computer backpack and my dont-leave-me perse. This volume allows me to carry my luggage in the cabin and my slightly larger bag permit some temporary extrats, like gifts or food. complying with air company cabin bags size saves money, time and prevents from loss.
I try to make it as casual as possible. I don't want to attract attention when travelling is smaller cities. Also I'm not treated as a tourist which I'm not.
The main backpack
I try to travel with a light 30L backpack which is fine for the whole year expect the cold season. Around the winter I go for my +40L compactable backpack that is waterproof.
It's less than 7kg total.
The slim computer backpack
it's a very light and casual bag. People don't realize a computer would ever be in there. I'm often distracted and forget that bag in restaurant. People have always run after me saying I forgot my bag.
It's very discreet and convenient to carry. I travel with it directly against my bag and my main backpack comes over it. Meaning it fits between my main backpack and my back.
It's also convenient when my computer is "home" and I go for shopping.
It's 1.5kg total.
The dont-leave-me perse
That's mostly useful at the airport. It's a tiny bag that fits under the coat when it rains and steal-proof; it contains my passport, 1 (one and only one!) credit card, my phone and my boarding pass or whatever I may need to take out rapidly and too often. Carrying such a perse avoids removing your bag(s) and digging into it, or using pockets that are easy to steal or lose from.
What to travel with
First thing is to learn how to get rid of almost everything. Being packed is the concrete achievement of your material clearance.
Here's a tip:
Prepare your luggage to go for 3 days visiting friends. Let's say they have everything home. That means you'll take 1 extra pair of pants, 2 shirts, 3 underpants, 3 pairs of socks, 1 sweatshirt and 1 jacket. You'll also need a toothbrush, ... Don't pack them yet but leave them in front of you. That's your essential.