There is a lot that goes into making good videos. These forums are filled to the brim on such topics and advice on how to grow your channel. I'd recommend poking around some more. But below I compiled a list in my opinion what goes into making a "good" video. I tried to keep my list more on the "Gaming" related side for you as to that's what I guess is your intended genre.
1. Clear Commentary Audio (No background noise, no hum, etc.)
2. High Quality (At least 720p if possible).
3. Consistency. (Upload weekly or daily.)
4. Walkthroughs contain as much information as possible without boring your audience
5. Relate to your audience. Entertain them, ask them questions, engage.
6. Length of video relates to type of video. 10-15 minutes. 20-25. Below 30 is highly recommended. Anything shorter the better.
I'm sure there are Gaming channel experts on these forums that can compile a better list with much more information then I could provide. But overall just get out there, create and you'll learn along the way. We all make mistakes but through those mistakes is how we get better. =] Best of luck!