Find keywords, topics, and possible titles:

• tubebuddy.com
• vidiq.com

Make live streams in an easy way and allow people to call you live:

• streamyard.com

Music to monetize your videos:

• epidemicsound.com
• youtube.com/audiolibrary
  

Make thumbnails, channel banners, and community posts:

• canva.com

Test thumbnails and titles to see which one performs best:

• thumbnailtest.com

Check how the other YouTubers are doing, but be aware that people who publish Shorts don't really make the money the websites suggest:

• socialblade.com

Verify if something is actually trending:

• trends.google.com