Based on my experience, you can optimize your YouTube videos by using the following strategies:
Speed up your voiceover - I noticed my videos became more engaging when I sped up my voice.
The key is to change the tempo without altering the pitch because if you play around with the pitch, you might sound like a totally different person.
This has boosted the overall engagement level and view count of my videos.
Use targeted hashtags - I cannot emphasize this enough.
Many people use YouTube as a search engine and use hashtags to find specific videos.
How do you find your hashtags? It's simple.
Look at your competitors and their channels and view their videos.
They usually have hashtags.
What I did was I got all my competitors' channels and went through as many of their videos as possible to compile a monster list of hashtags, and I put those hashtags in all my video descriptions.
Use only thumbnails that work - I know this sounds generic advice, but pay attention to my phrasing.
Use thumbnails that work, so don't go through the motions of putting a thumbnail because that won't work.
Pay close attention to what your competitors (especially the bigger ones) are doing.
What do their thumbnails look like? They were designed like that for a reason.
They use those thumbnails instead of generic ones because those thumbnails work.
They get clicks, so reverse engineer what they're doing.
If you need proof of this, there's a reason a lot of YouTube thumbnails show the creator with their mouth open or looking surprised.
People gravitate towards those thumbnails instead of plain text on a colored background.