Of course every grant is different, but below is a list of materials I kept from my Arts and Humanities Fellowship Program application to adjust and resubmit there and other places in the future. If you're interested but overwhelmed, maybe just start slowly gathering these things and tinkering with them... though I know nothing motivates me like a deadline (preferably with money dangling on the other side).
Artistic Statement - mine could use a one-two sentence version.
Resume - ideally one page, clearly delineated and sectioned. If you have the ability and familiarity to use Photoshop, try creating a striking resume there. If you aren't sure where to begin or don't have access to Photoshop, check out a free online design app like Canva. I've used each for my writing and acting resumes (which you can see below). Some good things to have on your resume: name and contact information, pronouns or other instructions for referring to you, produced and published projects ("selected works" if you decide to not include something on the list) and other germane experience, attended workshops or classes, awards, affiliated organizations.
Support Materials - think reviews, interviews with you about your work, quotes from customers/practitioners/collaborators. (I'd also start thinking about past collaborators who'd be willing to write you letters of recommendation.)
Work Samples - for me this is 3 -10 pages from my current favorite pieces, though I might have to look through other work dependent on the grant. This might be high quality shots or scans of your art or designs, video of you performing, easily accessible music files, etc.
Work Sample Statement - try to write a paragraph about each sample you might submit. Describe the origin, process, and tools in a quick sentence. How does this piece reflect your interests, questions, aesthetic? Can you directly tie it to something mentioned in your artistic statement?
W9 - Yeah, this, too! I've saved the editable pdf (from irs.gov) so I can fill it out and submit as need be for grants that pay in $$$.
Hope this helps and please feel free to reach out via my contact form or social media if you have any questions!