channel keywords

In the field for "Channel Keywords" on the Advanced Settings page.. Do I separate each keyword / keyphrase with a comma? and how many should be added here?

Hi Everyone, I would like to ask what your strategies are with respect to channel keywords and individual video tags. For individual videos tags, do you also include some channel keywords? For example for our channel, our channel keywords include such words as "toys" "kids" "fun" "games". Our...