Most of the resources I was able to find deal with writing a deaf character. I’ve split the different links into categories of deaf, blind, and missing limbs. I’m still looking for detail-oriented posts that are work for writing paraplegic and quadriplegic characters.

Disability in general:
Stephanie Green’s Writing About Disability

Adam Pottle’s Five Rules For Creating Disabled Characters

Dannie Morin’s How To: Writing Characters With Disabilities

Fuck Yeah Character Development’s On the Handling of Disabled Characters

Gimpunk’s Writing tips: How NOT to write disabled people

Amputee/prosthetic limbs:
The Trolliest Critic’s Roleplay Guide 025: Prosthetic Limbs (Character Guide)

Blindness:
Elsa S. Henry’s So, You Wanna Write Blind Character?

Fuck Yeah Character Development’s Do you guys have any idea on how to write a blind main character?

Deafness:
AbsoluteWrite’s Writing Dialogue for a Deaf Character forum thread

Fuck Yeah Character Development’s Advice On Writing Dialogue With Signing Characters

NimblesNotebook’s Any tips/resources on writing a deaf or hearing impaired character?

Rosamund Lupton’s Writing A Deaf Character

Disclaimer: I am an able-bodied adult and I’m not trying to say writers who do not have to deal with these kinds of issues on a daily basis are entitled to tell these stories. We’re not. But since there are writers who want to add accurate representations of what life is like with a physical disability to fictional literature, we should at least do our best to understand the most realistic portrayal. If something I wrote is insensitive, offensive, or wrong, please tell me so I can fix it.