Most youtubers asked me how to get sponsorship for youtube videos without having a huge number of followers. But the problem is the companies don't show interest in small subscribers base. it's pretty obvious because they need profit & for that they trust numbers.
At the end every company need growth in their business. So that first thing you should aks yourself before approaching a company for sponsorship why would they give you that opportunity.
Do you have enough audience or do you have potential to drive sales for company?
If you think yes then you can approach them directly, but its not a good idea. Most of the company approaches a creator to promote, sponsor or branding.