An avatar should just be whatever. I changed mine a couple times many years ago but quickly just felt that it doesn't really matter. What DO matter is that you stick to one you have just to get simple recognition in the long run sort of speak.
Stick to what you have, regardless. It's more important you have good content behind the avatar.
Your avatar should be something that has meaning to you, even if no one else gets it. Mine is half of a joint avatar between me and my husband. Alone it looks like a weird balloon thing but put it with my husband's and you get which makes a nice heart representing me and my husband's love. Mushy, I know, but I like it and that's what matters
I agree (to a greater or lesser extent) with *archangel72367; your avatar should be something you will enjoy having.
I've had my avatar (or versions of it; it's a 'new' version of 's avatar because people were getting confused between me and her by avatar alone ) for almost all of my deviantART life and I highly, highly doubt I will be losing it ever. Though it might not represent me now with its flashy goodness indicative of nooby caramell-dansen-loving boobs (which is definitely true of my past self; look at the clubs I run ), I love it to bits and know people think of me when they see it (provided they knew about me in the first place ).
Avatars are personal, they're individual and should be used to express you're personality, they can express a large amount of details and traits about you or even a specific single detail or trait. That's what I feel.