I generally loathe that expression "you never have a second chance to make a first impression."
It may be true, but it's still too quaint or too glib or too annoying for me to fully embrace. But I am somewhat fascinated by how closely the initial impression that you leave with others actually matches up to how you view yourself.
There is often a wide chasm between these two realities. 
I've heard on numerous occasions that people find me arrogant if they meet me in a group without alcohol being present and for only a short period of time. This might be partially true, although I like to think of it as a healthy confidence, however, people will usually mistake my silence for an air of superiority that I don’t necessarily wish to convey.
On the other hand, if you were to ask people who knew me in college they would claim that I was the most outgoing, sociable bastard walking around on two legs or occasionally crawling towards the keg.
I would talk to, laugh with and at the end of the night playfully insult nearly anybody, which all contributed to a 2-term fraternity presidency which was only rivaled by Abraham Lincoln and Genghis Kahn in both scope and utter domination. 
But I digress.
If left to my own devices, I lean towards introversion unless I've:
A) Been drinking
B) Am extremely comfortable around you
C) Feeling really pissed off for whatever reason
I do think it's important to know how you are perceived, but if you start worrying about it all the time then suddenly you're a politician (and nobody wants that). Being a chameleon, however, can be a nifty trick if pulled off successfully.
If not, you start adopting really pompous-sounding English accents for no reason at all and then you're Madonna. 
I'm in no danger of adopting Malawian babies or anything of that nature, and typically I don't care that much what kind of first impression I leave.
There are times when this policy doesn't fly and these situations can lead to hurt feelings and misconceptions and it can also easily bite you in the ass if you're not careful.
For those reasons alone, I think it's semi-valuable to have an idea of how others initially view you, at worst so you can manipulate them to your own ends and at best so you don't create unintended feelings or expectations.
What kind of an impression do you think you leave?
-BDS
I have also been called arrogant when I'm first introduced simply because I am quiet in new situations. I prefer to be quiet until I know the group I'm in. After I have become comfortable with the surroundings I will talk your ear off but until then I will be quiet.
I think i am generally perceived as outgoing and fun, certainly not arrogant. In fact i was out shopping with a co-worker and her friend i had never met the other day and she commented as such.
I think I'm usually seen as outgoing. It is always very interesting to me when people have met my husband first and then me they seem so surprised we are married. He tends to be on the shy side and is more quiet until he feels comfortable. However, I tend to be on the side of being able to talk to anybody.
I am actually kind of shy, but am perceived as more outgoing. I can relate to the alcohol thing...I am the life of the party and will walk up to total strangers and say the funniest things (or at least they are in my mind?)
Nipul - If I avoid my daily work I'll have no money to pay for high speed Internet and ultimately blog. Sorry.
Rob - I understand completely, and think there has to be a certain comfort level before I'm going to talk your ear off.
Miss Ash - I can buy that, and those are excellent qualities to have in people you want to hang around.
Sarcastic - I think opposites match pretty well in this regard as if you had two totally outgoing people they would probably fight and compete with each other. I bet yours trade-off works well.
Jlee - If something is funny to me - that's all that really counts as far as I'm concerned. It's usually funnier if said to total strangers as well.
It depends on the situation where I am first being met. I've mastered that chameleon thing pretty well ~ and still manage to be honest and true to myself. Generally, if people meeting me for the first time have a strong sense of self, then I think I am seen as confident. If not, arrogant. Of course, this and a buck fifty... :)
Snob or at the very least aloof. Definitely above the fray.
If they take the time to know me though they see someone completely different.
outgoing but i would MUCH prefer to be at home with a book. I just know how to appear outgoing.. its just exhausting
What you see is what you get. Hyper. Goofy. Mostly nice, but not enough restraint. Which is why I can't work in a real office. Among real people. No inner monolog.
And, guys, go to my blog site. I have an announcement you'll dig.
Apparently I come across as mysterious and brooding.
But if people take the time to get to know me, i'm very outgoing and welcoming...
Bostonpobble - I like the part about staying true to yourself as you can shift personas, but not at the expense of selling yourself out.
Melissa - Aloof is another good one, and as you noted, look a little deeper and that's far from the case I'm sure.
Anonymous - Who doesn't feel this way sometimes? I know I get my fill of being out too.
Wendy - I believe it and it works well for you. Very cool & I'll be over soon to check out the announcement.
Friday - Those are good qualities in my book as a little mystery is always a good thing - at least initially.
I've been thought of as stuck up only because I'm very quiet and reserved around new people. Once I know you, I warm up quickly. Put me in a crowd though and I fade into the woodwork : )
I get anything from cocky to shy. I dont say too much most of the time unless with close friends or with someone who has peaked my interest.
Know what? I'm always been bitchy! I feel like "Andrea Parker" taking care of the prodigies back to sanity. So, I don't really care what others think of me. I don't need to look good to please everyone. And God loves me for being me. It's only you who knows yourself not others so, be kind and trust your own self.
Symplyamused - I"m not much for crowds on the first meeting either, and reserved is a good word too.
Idig - You hit it with the peaked interest thing because that makes a big difference as well. If not, why make the effort?
Anonymous - Be kind is reasonable in nearly all circumstances, and while I don't think trying to impress everyone else is the way to go, I do think having an idea of how you come off can simply avoid misunderstandings which take too much time and effort to clear up.
I don't know what kind of first impression I leave, hopefully a good one.
I bet you do.