How to make good youtube videos?

Hi, i'm trying to make youtube gaming videos with me and my friends on xbox 360. I have a game capture card.

My videos are about lets-plays, walkthroughs, tutorials, strategies, and general fun. So far i have recorded two videos with my friends. One was on gtav and the other on minecraft. However, I'm having trouble making good quality videos because i have some problems such as:

Sometimes my friends voices are quieter than mine which is awkward.
It is also awkward to make the video look professional. I have trouble thinking what to say. At the beginning i'm like "hello, uh welcome to my video…" and it just doesn't sound cool. I also don't think my voice sounds great when I'm recording videos.

Overall, i also have issues of knowing when to record and when to pause, it just doesn't seem organized enough. People are talking at the same time so you don't know what anyone is saying.

What should i do to make my videos better? Do i need to script every video with everyone so i know exactly what i'm doing and when others should talk or does make up as you go along work?

Any opinions would be very helpful.

Thanks

Added (1). @vcbcfghftgh - that link didn't do anything. =P
I checked your channel too. Nice videos.

Find a video thats
1) super informative that no one has doen yet.
2) super funny. Those usually get really popular.
3) something that usually interests people.

But, getting your good youtube video well-known is another step.