If you ever read Glamour magazine they always have a page in the back called do's and dont's. It's always the highlight of the whole thing for me, I usually turn to it first. Now SL is a place for people to be themselves (which is not always in people form) and I totally respect that. Anyhoo, what brings all this to the forefront to me is I (attempted) to go to Designers United and nothing would rezz, I crashed several times in between barely being able to walk as it was. So I did a little fashion investigating in the form of turning on Avatar Render Costs display. If you don't know what ARC is you can read more about it here. The more stuff you have on - the more that stuff is going to effect everyone else. For a frame of reference - in a lag filled sim under 1000 ARC is best and of course the lesser then that the better. Lots of fairs and expos are even offering zero ARC outfits. Therefore, when you are planning to go to any kind of event where there is more then likely to be more then just a few people there (ahem Designers United) please leave your "look at me I'm on fire" outfits at home and check your ARC at the door, and Thank You.
For example: this girl had all kinds of shit and piercings hanging off of her. ARC was 3537
I don't know if it was her crow outfit or the crow antlers (???) but she was a whopping 8195!