Hello -- you're probably at this page because you want to know how to make something accessible to me as a Deaf person. I've written a more general primer on event access for d/Deaf and hard-of-hearing (DHH) people, and the first big point is that everyone is different, and you should ask each individual DHH person what they need. For me specifically, though -- here's how I'd answer that.
Schedules/notes/documentation/papers in written form whenever they are available. Interpreters and captioners will need them for prep as well, so please pass those on!
I prefer ASL (American Sign Language) interpreting as a main form of access. I'll need an interpreting team for the duration of the conference, including evening networking events; teams of two or more will rotate periodically in order to prevent fatigue from affecting interpreting quality. Not all interpreters can handle all scenarios, and I tend to get involved in complex, doctoral-level discussions in multiple fields -- so make sure the interpreting team can handle this level of event. I may be able to connect you to either locals who are well qualified, or interpreters who've worked with me in the past and can fly in for a high-level event.
Interpreters and interpreting agencies tend to want my interpreter prep letter.
If ASL interpreting is not an option at all times, in-person CART (realtime stenographic trancription) may be an acceptable way for me to access talks, especially keynotes/plenaries. If in-person CART is not available, remote CART with a projected screen is doable. As a side benefit, other attendees with hearing loss, ADHD (I have this too), dyslexia, auditory processing disorder, and English-language learners will benefit -- and you'll have transcripts of the keynotes/plenaries immediately afterwards.
Stenographers and captioning agencies tend to want my captioner prep letter.
I'm working on making my templates for access requests into resources that would be useful to others. One early version of this is a breakdown of how I send in a request for interpreting to a new person/event if I want to include a lot of detail. My approach is particular to who I am and the position I'm in, so my letter may or may not work for you -- adapt it to your own situation as needed!