The title and thumbnail make a promise. The opening needs to keep it. A useful YouTube strategy connects both decisions.
Make one clear promise.
A topic can be interesting without giving someone a reason to click. The packaging needs to explain what is worth understanding and why this particular video will be useful.
A title and thumbnail should work together. Repeating the same information in both wastes space that could add context. The choice should also accurately represent what the video delivers.
Get to the reason someone came.
The opening should establish that the viewer is in the right place. A long introduction can delay the answer at the moment someone is deciding whether to stay.
The right opening depends on the subject. It may be a question, an example or a direct explanation of what follows. The useful test is whether it connects to the expectation created before the click.
Read the result as a connected story.
Click behavior and retention can point to different problems. A promising topic with weak packaging needs a different response from a strong click followed by an early exit.
Use the available evidence to form the next practical test. Change decisions you can explain, then carry the learning into the next production.