I don't know much about twitch other than to make sure to have time to stream but with YouTube I'd say make sure to have a good thumbnail, take note of your quality, before exporting your video make sure to triple check your video edit, and if you have social media accounts, make sure their linked up to your YouTube and each of your video uploads.
I've helped a couple friends and clients and that's the best tips I could give yea mate! Goodluck!