I think I'm going to make a "Let's Play" series on Youtube...

Any tips for a newbie? Like, should I just talk on impulse or write scripts, etc?

I like it when people talk naturally and when it’s obvious that they are talking as they are playing.

You can always go back and edit the audio track to get rid of excessive ahh, and uhms, etc.

What game?

A few indie games at first, I think. Like 1916 and One Late Night. I’ll probably move on to a few Oblivion videos with the 28 and a Bit zombie mod. You can’t go wrong with zombies XD

Here’s an older thread about Let’s Play where some advice was dispensed: Need "Let's Players" help - The Game Room - Straight Dope Message Board

Do not use a camcorder.

Make sure your microphone is half-decent.

Do not leave in footage where you had to set up your recording equipment, get your cat off your lap, etc.