Announce who you are!

Speak clearly and at consistent volume
 - Don't mutter or trail off
 - Try not to yell too loudly

Think about what you're going to say before you start talking
 - Is what you're going to say adding anything to the experience?

Be knowledgeable about the overall game and the players
 - Use your knowledge to explain things like game plans, conditioning, and choices/adaptations players make
 - Try to keep the BradyGames Ultra Street Fighter IV Bible instead of just guessing
 - Keep a matchup chart handy
 - If you have zero technical or general knowledge, you probably won't make a good color commentator

If you also play a character in the match, use that knowledge to explain the matchup or decisions better
 - Don't constantly point out player X could've done Y or you would have done Z instead

If it's 1 or 2 scrubs on screen, don't constantly point out every simple mistake they make and say their bad
 - The viewers can probably tell that on their own

It can be difficult to be entirely unbiased, but do not be a cheerleader throughout the match

Don't describe what's happening in the match
 - That's what video is for
 - Does not apply to explaining unique or un-obvious interactions(i.e. Marvel)

Don't talk to people off-camera/off-mic
 - If you do have to, cover your microphone and explain on microphone what the other person said

Don't commentate if you know you'll have to leave and play a match very soon


Don't interrupt the other commentators
 - If it's not something super important, let it go
 - If both commentators keep interrupting each other then reverting to awkward silence like a first date, both need to establish a better rhythm

Ignore trolls
 - Don't respond, interact, or be like 'omg he got banned!', like you're someone new to the internet

If you're responding to something in the chat, repeat what was said
 - Streams can have 30 seconds or minutes of delay, but the chat is instant