FlashToroGaming
Loving YTtalk
It all depends on the audience you want and the community you desire to grow. Some people enjoy informative commentaries and just casual talk. Although I'd say the most popular would be humorous commentary which is hard to do if well, a person isn't funny. The best you can do to discover your commentary style is do some practice runs and just talk however you feel to keep it going and discover your non monotone voice and how you truly sound like.
MrMauriceTL
Random Let's Play Gamer!
You just got to find your own style, the style where you are most comfortable with! If you be yourself your videos will be more natural and you will get better and better at it over time. 
CaptainDelugo
Even Blackbeard is scared of me!
Either what these people above me said or you become a try hard like I am 
Cabbage Hunters
I Love YTtalk
Yeah, like they said, do what works for you.
A couple tips - dont be monotone, keep your voice fluctuating.
You gotta react to things more vibrantly than you would in real life.
Keep in mind that you can edit things later to make it work. Don't be afraid to say something you can cut out later, or to make a bad joke that you can put some sound effects in with to make it funnier.
Editing will always be your best friend.
A couple tips - dont be monotone, keep your voice fluctuating.
You gotta react to things more vibrantly than you would in real life.
Keep in mind that you can edit things later to make it work. Don't be afraid to say something you can cut out later, or to make a bad joke that you can put some sound effects in with to make it funnier.
Editing will always be your best friend.
You can talk about anything honestly, you can shout and laugh the whole time ( like Kwebbelkop, pewdiepie, ... ) or you can talk about something serious ( like gbay99, ... ) or something in between. There's an audience for every type of commentary. You could focus on how to play the game or just talk about something else or just have fun with some friends and annoy eachother in the game ( make it funny ) there are so many options.
PrettyGamer
I Love YTtalk
I have read from a blog some things that are good to put in one of your commentating videos. One is to tell something about yourself. I think this is a good topic for beginners especially if you want people to know who you are. 2nd is something that is happening on the game or you can make some different stories that is related to the game. For example your playing octodad and there is a wedding going on you can actually put something about a story that happened like when I ask my mom if we can marry some classmate and she said no because we're just 5 years old <although the boy I want to marry is 5 years old>. Then you can also read some of the comments of your viewers so they can feel that your including them in one of their videos. You can also make a fact about a certain countries culture that you can relate w/ the game. I have listed a compilation of those things that you can put on your video games commentating channel coz I also have the same interest as you do.. 
sometimes I write it in my notebook as a part of a script whenever I'm playing a game.
sometimes I write it in my notebook as a part of a script whenever I'm playing a game.
CuriousDave
Well-Known Member
Try different things out! I'm by no means a Youtube-guru but I feel you come across as more proffesional when you're just being casual, don't mind if t gets quite for a couple of seconds (even though I usually cut that out in my videos...) and just talk like I would talk with a human being! Treat the camera as another person you're having a casual chat with while you're playing a game together! Lately I've started to warm up by just starting my cam and then just talk nonsense! It both warms up my voice and makes me relaxed enough to not feel that I don't have to talk constantly!