Great idea for a thread!
What do I have to prepare and be mindful of if I want to spend a kinda long time somewhere abroad
Think logistics.
1.
You need a packing list, which will be influenced by the climate among other things. Figure out when you're going and look up climate patterns during that time of year. In most places you just have to worry about the rainy season and/or temperature and stuff like that, but you might as well just read about the place and what it's like when you're planning on going there. Will it be cold at night? You might need to need extra warm clothes to sleep in. Will it be windy? You should bring a windbreaker. Is it possible it might rain a lot? You might need all sorts of extra things. Read up on the activities you plan on doing and read up on them, and see what things people usually bring. Are you going on a long hike? Maybe you'll need extra batteries for your camera. Will you be doing any river crossings? Maybe you'll need some gaiters.
I break down my packing lists into: Gear, clothing, first aid, electronics, toiletries, and if I'm going hiking and bringing food then that gets its own category too. And "Other" which contains my wallet, passport, etc. I do this because it makes it easier to find things on the list, and at the end I just print the list and check things off one by one as I pack them. When I'm packed I can be 100% sure that I have everything I planned on bringing.
2. You need to see if you're actually allowed to go to the place you want to go to, and what sorts of steps you have to take in order to be allowed entry (if any). Your government should in theory have this all online somewhere, an entry for every foreign country, and an explanation of what you can expect, and what's required. If not, find that information somewhere, make sure it's up to date, and read up on it.
You might need a visa, your passport might have to be valid for the next 6 months, etc. Most countries also limit your stay as a tourist, and this can be influenced by how you cross the border (via land or air, etc). If your plan involves crossing multiple borders, at different times, you need to check what sort of visa you get on arrival in each country and make sure the timing works out.
3.
You need to look up if you need any shots for the place you want to go to. I recommend visiting a travel clinic and letting them handle it. There might be mandatory shots, and there will probably be a bunch of optional shots and medications that they will recommend. You don't have to do all of them, maybe read up on it a bit and make up your own mind, but I highly recommend the traveler's diarrhea medication (which you have to start taking a month before your trip IIRC) and the hep A&B (twinrex?) shot is probably a good idea too. Other than that usually the only thing required are special shots for more tropical regions (malaria, yellow fever, etc.) If you are going to be crossing the border of two tropical countries, they might have rules at the border about what kind of shots you need to have proof of when you cross.
4.
Read up on local customs and social norms. Every part of the world is different, and many of the differences are unexpected. Many can also get you into trouble, so you might as well arrive knowing how to say hello, when to bow, when not to bow, whether to tip and how much, what to not step on, where not to wear your shoes, proper hat etiquette, and all the other cultural quirks that we usually take for granted. On my first day in a new place I also usually take it easy and spend some time relaxing in a public place where I can maybe sit down and eat and watch the way people move and interact. Every place has its own way of doing everything, and the faster you figure out the quirks the better
5.
Figure out a contingency for every probable enough medical scenario. If you have high blood pressure, see if it's okay to bring high blood pressure medication over the border (probably), figure out how much you'll need, and see if you can get some there. Make sure your first aid kit contains all the things you'll need that you can't get there. Make sure you have good enough health insurance for your trip as well, and consider scenarios such as "I broke my leg and can't get up". It will probably not happen, but it easily could, and you don't want to end up in a situation where you have a giant hospital bill and you're stuck in some confusing situation with people who speak a language you don't and have rules and agendas you don't understand either. Meds I usually bring with me no matter what: pain pills (I walk a lot on my trips and my knees suck), tylenol day+night, diarrhea meds (stoppers + goers), bandaids. Covers 99% of all medical type situations. For the other 1% you want health insurance. Some countries might have a problem with some medications, I've heard stories of people bringing some form of tylenol through the U.S. and having big problems, so read up on all the stuff you plan on bringing, through all the borders you plan on crossing.
6.
Read up on common local scams and be ready for them. Also read up on common "tourist mistakes" and pitfalls. This could include anything from "Don't walk to this part of town ever" to "watch out for pickpockets" to "don't eat at restaurants right at tourist traps" to "when taking a taxi follow these 4 important steps".
7. Figure out if you can even afford going there.
Look up how much things cost and draw up an average daily budget. Figure out where you can cut costs, if necessary, and where you can afford to splurge a bit. See if you will have to pay a fee upon arrival. Even if you don't, it might make sense to bring some local currency with you. Look up if credit card usage is common and figure out ahead of time how you're going to pay for things. Look up what cash is required for, if anything, and be ready for it.
8. If bringing electronics
look up what plugs you'll need, and check every piece of equipment individually to see if it's compatible with whatever local electricity setup exists. These days I think most modern devices will work just fine whether you plug them into 110V or 220V, but in some places the conditions might warrant a surge protector if you're going to be using something like a laptop. Bringing a small portable battery (Anker, etc.) is also often a good idea, as it is not good to lose power when you're in some new place and your only map is on your phone.
9.
You need to figure out how you're going to be doing laundry, what the logistics of that are going to look like, how that affects what you're going to bring exactly, how much it's going to cost, etc. More specialized fabrics usually have very specific washing instructions, so if you have merino wool as a base layer for example, you don't want to be washing that stuff with the rest of your clothes every 3 weeks.
10.
You need to figure out the best way to pack up all the stuff on your packing list, and the best mix of backpacks and bags to bring, depending on what kind of trip this is, and what sort of activities are planned. I usually like to bring a big 70+L backpack, so I have an easier time transporting all the stuff I have from A to B, but on most days all I will have on my back is a small daypack. On some types of trips it makes sense to bring a medium (30L or so) type backpack, and other combinations of all 3. I also highly recommend packing cubes (google it, they are cubes for clothes), they will really optimize all your clothes and how much space they take up.
11. If you have specific
dietary requirements, it would be wise to read up on how to avoid the stuff you're supposed to avoid.
12.
Look up the different ways that exist to get around, whether it's subways, buses, trains, car rentals, flights, or boats. I recommend having a clear plan on how to get to your hotel from the airport when you first get there. I also recommend making use of public transit in some capacity on one of your first days there.
13.
Figure out how you're going to access the internet. Look up SIM card options, wifi, pocket wifi, or whatever infrastructure exists wherever you're going.
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