Do not post photos of dogs or cats, regardless of how cute they are.
Avoid using any version of, "that which does not kill me makes me stronger" in your headline.
Ladies, do not use the adjective "successful" when describing the kind of man you would like to meet. What does that mean? As in, not a loser? Well, no ****!
If you are "quick-witted and funny", say something witty and funny.
If you are "attractive", post attractive photos of yourself.
If you are "awesome", describe what it is that makes you awesome.
If you are "intelligent", ensure that you know how to spell it correctly and provide timely examples of your keen insight.
Do not play the naive game: "Gee, what am I doing online? I've never done this before. A friend put me up to this." Um, yes, you have... and no, they didn't.
Women generally require that any prospective male companion possess a minimum of two of the following qualities: Taller, richer, or smarter.
Men, take notice. If you do not qualify by the above standard, do not waste their time.
By contrast, men generally look for women who are prettier, emotionally warm, and youthful.
Be prepared to eat rejection for breakfast every day. Online dating is about as fun as writing resumes and doing panel interviews.
Women, if you are even remotely attractive, be prepared to fend off armies of unqualified suitors who have not read a single word of your profile.
Skip daydreamy descriptions such as "wanting to walk hand in hand on the beach". Long-term couples spend only a fraction of their free time doing that sort of thing.
Oh there's so much more but I'm out of time. Got more? Post them here.