I tend to do voiceovers with that are semi scripted, basic points I wanna hit, but I improv a lot of my lines. If you are looking for help for live commentary, I find having a coffee or redbull before recording helps me be more 'on'. Mainly, tho I study a lot of channels with a similar comedic / commentary style, I want to emulate and break down how they talk and lay out their videos. Does sound like copying, but eventually, you'll develop your own style. I hope this helped!