This is how I have my camera mounted since you said you were having mounting issues. My helmet has a deeper curve on the bottom than most so it should be fairly straight on any other helmet, It's pretty straight on mine but you can tell it's slightly off.
Also, having a set topic for your rides will help you make a better video. You don't have to do it all in one go. Take time to talk about it over your ride and edit to the parts where you start talking about it. It doesn't matter if you think the topic isn't important to anybody else, if it's something that you think is interesting and want to talk about then just talk!