Firgure out what kinda info you want I have in the stream. Once you know why you want to display, you can start to mess with positioning of it.

A personal tip I follow and recommend is that simpler is better. Don't go crazy with graphics or text or shrink the gameplay too much since that is the primary focus anyway.

I have the design skills of a potato so I can't offer a ton of tips, but it's honestly a lot of work to find something you really like. Just keep trying things and look to others for examples of something you might like for yourself. Just tweak it a bit to match your own unique style if you do that.