The way to attract people to your channel with your banner would have to be, make the colour's and design's resemble and compliment each other. Another factor is to make the design's relate to the topic you will be uploading on your channel, so if your making a gaming channel don't use tubes of lip gloss and makeup as designs because that doesn't relate to gaming, use controllers or headsets. The colors should be flashy and resemble the topic aswell, pink = beauty, etc. I like to use gradients in my text because it makes the text a bit more flashy and cool looking. Hope this helps you out! Finally, the first thing you usually see of a channel is either a video thumbnail or their avatar, so don't worry too much about your banner (it's important though) and worry about your content, thumbnails and your profile pic! Good luck!