I've been 100% WFH for a super long time, and it recently came up that a few people would like to hear what I know about it. So here that is. May not apply to people who do field work, but it might.
- You need an actual office space at home
Working at the kitchen counter is doable for a short period of time, or as a change of scenery on occasion, but if you're doing desk work at home, you will be happier with a proper space distinct from your living area. Preferably with a door that closes and locks.
The first reason for this is that it will help you to maintain differentiation between "work" and "home", because your work will probably have expectations that you're "always on" and your housemates (family or not) will think you can just drop everything to do whatever task or chore they present after barging through the aforementioned door.
The second reason is that, in the US, you can deduct for home office space if you only use that space for work. It's not a lot, but it's something.
- You need proper "office stuff"
A decent desk, a good chair, whatever keyboard and pointing device you prefer most, noise cancelling headset, good monitor(s). Spend the money on these things; it's well worth it.
- Do get up from your desk often
Your back and legs and eyes and mind will thank you. Deep vein thrombosis is no joke.
- Don't work outside your regular working hours
This one is really important. Obviously, different jobs have different demands and requirements, but do your best to ignore calls to "do work" outside of your regular hours unless it's a legit emergency or scheduled in an agreeable fashion. You've recovered your commuting time; don't just give it back to the company.
- Change it up
If it makes sense to do so, pick up and work from the kitchen countertop once in a while. Go spend some work time at a coffee shop. Just being around people is a necessary part of being a functional human.
- Your social skills may degrade
If you had any to begin with, of course. You can maintain these by being extra chatty with cashiers, people running garage sales, random people you pass by in the store.
- Force yourself to leave the house
Another really big one. This goes double if you're in a household where someone else does a lot of the shopping. Between that and the "delivery culture", it's real easy to go "Shit ... when was the last time I was even outside?" Very very important in the winter, because then it becomes "When was the last time I saw actual sunlight?"
- Keep your space tidy
Especially if it's behind a closed door, it's easy to let tidiness slide, because who else sees it anyway? (This is one I need to do better with for sure.)
- Communicate very clearly
Communication between people who are remote from each other at work is definitely a skill. You have to dance between being explicit enough that the other person(s) understand exactly what you want them to while not coming off as condescending. I'll "bookend" those kinds of things with a "You probably know all this already, but it demands being said just so we all know that we all know" before and after the message. I'm also aware that different cultures approach communication differently. Some of the people I work with are in Germany, and they can be very dry and "just the facts". You may need to adjust your communications based on who you're talking to. On a related note, give other people the benefit of the doubt when they are communicating "less efficiently" with you. You might need to reword what they're saying back to them to make sure that you understand. This is another one of those place where it can appear condescending; bookend that with a "I'm just making sure I understand you" thing.
I have made (or am currently making) mistakes with every single one of these points. I'm sure there are more I'll think of later.