Replying to Advice on Contacting Companies for Sponsorships (Not Skiing)

To preface I'm a photographer/ cinematographer with a relativity large social media following.

I've noticed how other photographers with large followings get "sponsorship" from clothing, headwear, backpack companies & similar businesses. Obviously, it'd be cool to get gear from people, and in turn promote their product.

People with experience reaching out to these kinds of companies, what's the best way to go about it?

People who are a part of these types of companies, what do you look for when someone does reach out?