Think about millions of people around the world, they will watch your video. So it must be entertaining and interesting. You can capture fun of your kid, pets or any thing which viewable by a family. Make sure you don't violate the YouTube Terms of Service.
You'll definitely need a video camera (can use your Smart phone) or if you're animating, an animating program and also a profile on YouTube. It’s free. Log on to YouTube and set up an attractive channel.
Think about the audio, make sure it’s entertaining and interesting. Edit your video; it can't be more than 15 minutes long unless you are a partner with YouTube. Save it as high quality video file (HD Video).