First, make sure that you are qualified for the campaign that you are applying for. There should be a description of the type of creator that the brand is looking to participate.
Secondly, audit your social channel. Many brands have strict guidelines that may prohibit them from working with creators who post content with explicit language, religious and/or political content, or highly polarizing opinions. If you do not wish to limit your public speech, that is okay! It just means you need to find brands that align with your values.
Make sure if you are asked to provide a Pitchback (content idea) that it aligns with the messaging outlined under the "Campaign Details" tab.