TheShareWay is a great place to start. See How to Find Companies that Donate for more.
Every company has a different submission method. Some will require you to submit a letter while others have forms with individual questions. This format prepares you for all types of applications. See my example pitch letter.
Applying for donations is a big project. From working with the nonprofit community, we have learned that it is very difficult to do everything all in one sitting. We suggest breaking it up over a few days and prioritize the ones with deadlines the furthest out.
I won 30% of the 62 companies I contacted. Of the companies that said yes, 50% said yes from the first outreach, 22% after the first follow up, 22% after the second follow-up, and 6% after the 3rd follow-up.
This helps you build good relationships. See my example post-event email.