The metadata for your channel is very similar to the metadata that you write for your videos, as you're able to optimize the description and tags related to the channel, as well as the actual name for your channel. Channel metadata optimization certainly plays a part when it comes to getting your channel out there and enticing potential viewers into becoming subscribers.

Channel Name: Now, this is the real difference from video metadata, with this being the title of your channel across the website. There are plenty of YouTube channels out there that use a culmination of branding and keyword targeting here, considering that this title will be shown in searches. This also gives people who aren't aware of your content an idea of what your channel is based around, so it's probably the best course of action. Here's an example of this:

With the impending release (as of writing this) of FIFA 14, this chap named Nepenthez has included both his channel name (or brand, if you will) and the term "FIFA 14 exclusive gameplay", which actually isn't misleading.

With this in mind, you should go for something concise, but also include a rather short tail keyword which you've previously targeted, as well as your actual channel/brand name.

About: This is completely similar to the version that you'll be writing for your videos, considering that you have 5,000 characters to work with, and the first few words/characters of your description will be what is displayed in searches. In video descriptions you should properly describe the contents of the video, and with your channel description/about section, you'll be describing what people can expect to see from your content, enticing them to subscribe and follow your online presence. Whilst doing so, make sure to include relevant, targeted keywords within the text; preferably towards the beginning, the part that will show in the SERPs.

Below is the channel description of Rooster Teeth, a US entertainment company whose content is created within video games. They've included the main contents of their channel in a very concise way, as it will be displayed in search results, and have written up a schedule for their content, which is a superb idea. It adds value to your description, and is certainly very enticing for potential subscribers, as it will give them a proper idea of what they can expect.