1. Conduct your Keyword research first as you will need you important keywords for this process. Keywords are valuable in the meta data of each video.
2. Look in your YouTube Studio Library and assess the most successful videos. 
   1. Look at the title, description, and category tags 
   2. Look at the thumbnail is the image compelling?
   3. Look at the language settings and transcriptions. 
   4. Is there anything valuable that you can learn from these successful videos and apply to the others? 
3. Look for videos that are a series: part 1, part 2, etc 
   1. Edit these videos together making an end screen so people can start the 'part two' video by clicking the card at the end of the 'part one' video 
   2. Of course update title, description, categories, and language settings
4. Descriptions should be keyword rich (that is words that are frequently searched that would be relevant for this video) and also include a website URL to a relevant page providing more information after someone views this video.
5. While looking through and watching some of these videos, take note of interesting 10 to 15 second snippets that you can convert into a YouTube short. 
   1. On the YouTube app, use the remix feature to extract a short snippet and submit as a short.

References:

SEO 

SEO: Keyword Research 

https://backlinko.com/how-to-rank-youtube-videos

https://backlinko.com/hub/youtube/youtube-keyword-research

External Article: YouTube Remix Feature