As a rule of thumb, you should use common sense and empathy when interacting with people with disabilities. Ultimately, people want to be treated with the same respect and dignity, regardless of ability. Following these basic etiquette tips is a good start.
Don’t assume someone needs help just because she has a disability. If the environment is accessible, people with disabilities can usually get around independently.
People with physical disabilities may depend on their arms for balance, so grabbing them - even in a friendly or helpful way - could affect their balance. Also avoid touching their assistive devices and equipment, such as wheelchairs without permission, as that is considered personal space.
A service animal is there to serve a person with a disability, to enable them in some way. It is not a “regular” pet, and should never be treated as such. Unless you have explicit permission from the animal’s owner, you should NEVER touch or interfere with them, even if they’re not working.
The best judge of what a person with a disability can or cannot do is themselves. Never make decisions for them about participating in activities; it is disrespectful, and may violate discrimination laws.
When people with disabilities ask for an accommodation, it is not a complaint. It displays that they are comfortable enough to ask for what they NEED. If there is a positive response to a reasonable ask, it will improve the person’s self-esteem, and increase the likelihood of them self-advocating in the future.
First and foremost, always speak directly to the person with a disability, not to their companion, aide, or care assistant. Talk with them as you would with anybody else; make small talk, explore hobbies, and ask how they’re feeling. Respect their privacy, and do not bring up their disability if you are not familiar with them.