In order to teach someone something you need to have a good knowledge of it already - Im not sure you're going to get the responses you want from the forum. For example, I can create secure VPN networks on Windows, I want to learn how to do it on a MAC platform. In order to teach someone this, you need to have a good knowledge of it yourself. You can go off and learn it yourself in order to teach others, but then is it something you will enjoy doing? Whats stopping me from learning it elsewhere in the first place?
Probably best to look at what you enjoy doing, then share that with others. Let people learn from what you enjoy doing naturally. People always find it intersting looking into others lives and what others can do, and those who enjoy the same, or want to learn it your way, will find you eventually.
Ive alway felt that people shouldnt need ideas on what they should do on their channel. Its YOUR channel, and YOUR content. You should come up with the ideas, then share the ideas here to ask opinions, rather then asking for ideas in the first instance.
Just my opinion