While there is always room for specific feedback, it seems that the vast majority of the time, a lot of the advice remains the same. A few things come to mind. Below is a list of probably some of the most common things I've seen over and over. Did I miss any?
When it comes to pictures, Velma has this pretty much sewn up, so people should check that out first. Not sure how that happens, but it has become a sticky thread that always appears at the top of this topic.
Treat each section like a question. For example, treat "Looking For" as "What are you looking for?" (i.e. Looking for a couple for MFM, a SF to attend parties with me, etc.)
Ask yourself if what you put in each section fits best in that section. For example, don't put a description of yourself in the "Looking For" section.
There is no need for words to describe things that your pictures and toggles already show (i.e. height, weight, body style, etc).
Keep the content positive. Negative experiences are the exception, and you'll look defensive and jaded if you dwell on them.
The term "Like-minded" by itself is meaningless. People need to define what that means to them.
A tag line should be witty, positive and catch my interest, if possible.
Everyone knows you are here for sex. Many (if not most) want to hear about things besides that, to see if you have common interests and things you can talk about.
Don't cut/paste in that toothless warning about using your content (i.e. Syndey University study). Best case, it makes you look gullible.
DO cut/paste your profile into some sort of word processor to find/fix spelling and grammar issues. Note, Google Docs is free and can be brought up in a browser.
Do not repeat the same things in multiple sections of your profile.
Do not leave any sections blank, or take the typical cop out about fantasies and say something like, "We'll discuss this when we meet."
Keep it positive, and try to end the last section with a positive thought.