If you need a short answer, Content. If you are delivering high quality content on a regular basis, You don’t need to do anything else and the sponsors will come looking for you (if you are that good). But if we look at step by step on how to earn money through sponsorship on YouTube, you first need to build a strong following on your YouTube channel. Here are the general steps to take:

1. Build a following: You need to have a decent number of subscribers, views, and engagement on your YouTube channel. This shows potential sponsors that you have an audience they can reach.
2. Create quality content: Sponsors will be interested in channels that produce high-quality, engaging content. Take time to produce videos that are visually appealing, well-edited, and informative or entertaining.
3. Determine your niche: Sponsors want to work with channels that align with their brand and target audience. Determine your niche and target audience to attract relevant sponsors.
4. Reach out to potential sponsors: Once you have established a following and created quality content, reach out to potential sponsors who align with your niche. You can also sign up for influencer marketing platforms that connect influencers with brands.
5. Negotiate a sponsorship deal: When a sponsor is interested in working with you, negotiate a sponsorship deal that benefits both parties. The terms of the deal will depend on factors such as the duration of the partnership, the content requirements, and the payment.
6. Disclose the sponsorship: It's important to disclose that you are working with a sponsor in your video or description. This is required by YouTube's policies, and failure to disclose could result in penalties.

I hope these tips helped. The start of the journey is always steep. So keep working hard. Hustle. Good Luck!