haihai, so a lot of this depends on what kind of disability your friend has, but I think I can boil it down.
1. Listen to, and believe your friend.
If they say “i cant do that”, believe them. Ask them if they’d like help, or if you can find an alternative. If they say “I can do that,” and dont need help - also believe them. Don’t force your help on them without asking just because you think they need help. You can ask if they want help, and then if they turn you down - listen.
2. Understand that disability is not linear
I know this sounds odd, but depending on their disability, they may be able to do something one day that they were not able to do the day before. Similarly, they might not be able to do something today that they’ve been doing just fine recently and you’ve seen them do before. This, again, goes with the listening and believing them. If they say they can’t do something, even if you’ve seen them do it before, understand that disability is not the same every day for every person, and don’t say things like “but I saw you do it yesterday!” or etc. Just listen to them.
3. Don’t touch or move them and/or their aids without permission.
I’m forever going to be angry that this has to be said, but it’s an unfortunate truth that it does. Many wheelchair users find strangers pushing them out of the way, or grabbing the handles on the wheelchair to move them or try to “help” them (and many times end up dumping the wheelchair user out of their chair and onto the ground in the process, sigh). Don’t move someones wheelchair - whether they’re in or out of it - unless they give you permission. Don’t move someones cane out of their reach without permission, even if they’re not currently using it. Or their walker. Or their oxygen. Or their hearing aids, or - literally anything - if it’s in the way, just ask them. “hey do you mind if I move this to the chair so I dont trip on it?” etc. And then listen.
4. Think about them and their needs while making plans
One of the most disheartening things with disability is when you get invited to go somewhere, only to find out that you cannot go because of accessibility issues. Especially when those issues are obvious and your friend doesn’t seem to care or even think of you. If they’re in a wheelchair, call and ask if the place you want to go to has any stairs, and a ramp if they do, before inviting your friend out. Ask about disabled bathrooms. Scout ahead if you need to. If your friend uses a cane, inviting them to that cool new pizza joint that you have to climb a staircase to eat at, isn’t going to work. If they have fatigue issues, a club with little to no seating isn’t an option. If they have dietary needs, make sure the restaurant you’re going to serves options for their needs (Gluten free/dairy free/vegan/etc). If the place you’re going to is busy and might not have parking close by, ask them if they’d like to be dropped off outside if you’re carpooling.
Just think about their needs, and if you’re in doubt, ask them what they are! If you’re worried that you won’t be able to anticipate their needs, and you’re too shy to ask, but still want to hang out with them - ask them to pick a place to hang out!
And finally - mistakes happen. If you do have plans to go somewhere and you both show up only to find out that your friend can’t get in the door, leave. Go somewhere they CAN go. Speak up for them if you’re with a group. “Hey! This isnt going to work, *name* can’t go inside, we need to find somewhere else to eat”. Your friend can speak for themselves, but it feels immeasurably better to have someone else have your back. Don’t continue your plans with the group if your friend can’t, because that’s excluding them to go on a long frustrating trek home, disappointed and probably a bit pissed.
5. Lastly, be understanding.
Don’t shame them for not being able to come out with you all the time. Or for taking meds. Or needing to go to places that accommodate them. Or for things changing. Understand that they know their body much better than you or any doctor does, and respect their boundaries. Assume that everything they do, they do with the knowledge of how it might harm or benefit their body, and you don’t need to tell them to do or not do things. Just accept your friend where they’re at.