My advice is to not give a wet slap. A rating is just to let you pick good opponents.
Nervousness in Rated Games?

thanks for the advice, I find that whenever I play chess in real life against opponents in front of me, I am not nervous. I don't know, its something about knowing that I am playing against a real live human, the as much of a capacity to make dumb mistakes as I do, that makes me relax. When I play against someone online, it feels so serious, if you will, in a way I suppose its because I can't differentiate whether I am playing against a computer or not (of course I know I am playing against a human, but playing chess online has the feel of playing against a computer, if you know what I mean).
Besides, in real life, I can see an opponents hesitation and facial expression. Knowing they are doubting their own moves really reminds me that my opponents human to, not just a machine.
Anyway, any more advice?

Rating shadows your real playing strength. Don't let it bug you when it goes down for 1 game (or up for 1 game). What changes your playing strength is your mindset (as you've pratially alread mentioned about being relaxed).
But what I mean is to get better you have to have losses. If you won every game you ever played, other than getter really boring, you woudln't ever know about certain errors. And so losses are learning opportunities. So is your mindset "I have to prove myself in this one game / series of games" or is your mindset "I'm an improving player, teach me something!"
And improving doesn't mean bad. GMs study their, and eachother's, losses like crazy to get just a bit better all the time.
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So my advice in a nutshell is to look at the big picture. You don't have anything "on the line" as first of all your rating only shadows your strength (it's sometimes higher, sometimes lower), and so game to game fluctuations don't mean much.
And there is actually something on the line, and that's a learning opportunity. And if you play you best (creative, relaxed, etc) and lose, you'll learn more.
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Of course you can understand all that and still be nervious. Don't have good advice for that one. I agree with you, you need to play and lose more to get used to it :)
Maybe this will help... whenever I have a spectacular loss I remind myself even professional players have these kinds of games. Endgame books are filled with lessons called "tragi-comedies" where the winning side blunders into a draw or loss. Or money round tournament games where a master throws away a piece and has to resign. So it may help to put it in perspective this way too.

Maybe put on some music you enjoy to set the mood :) Sometimes I put on fun music to play blitz, and I can enjoy the game in a different way. I'll feel free to try out fun/crazy ideas.
Or I'll put on slow music and end up thinking a long time and lose heh.

You're taking ratings too seriously. Your rating is not a number that represents your personal worth in the world or your intelligence. It's a number that indicates your skill in a boardgame and its only purpose is to help you find opponents that will give you a reasonably challenging game, as opposed to a ridiculously easy one or an impossibly hard one.
My advice would be to desensitize yourself to this nervousness by playing only rated games from now on - I can't see any benefit to playing unrated games? The more rated games you play the more precise your rating will become which equates to more opponents of equal skill which will equate to a more satisfying chess playing experience.
The chess rating system works over a fairly large sample size and is pretty forgiving to the odd blunder. Losing any one game isn't really going to effect your rating all that much.
So, chill.
I find that whenever I play rated chess games, I always get very nervous, this is becuase I know my rating is on the line, and even though I know my rating is already underrated (I play alot of unrated games) I still get very nervous.
Because of this, I generally play alot better in unrated games than I do in rated. I know my rating is not on the line and I am free to explore and perhaps follow through with some more unorthadox and creative strategies.
Does this happen to anybody else, they find themselves playing a bit worse in rated games than unrated ones? And if so, do you have any advise to calm me down?
I suppose I should just play as many rated games as possible so I am exposed to the feeling.
Thanks