I have mixed feelings about giving friends dating advice. Part of me is flattered that they ask; part of me thinks I give good advice because I've been in a ton of different situations; and part of me thinks, "Seriously, what part of my current situation makes you think I should be advising anyone?"
The truth is, it's like anything else. Some things I can give advice on - other things, not so much. Something I am reasonably good at, and therefore comfortable giving advice about, is how to write an online dating profile.
Google "how to write an online profile" and you'll get more results than you can handle. I sat down with a friend not too long ago to write a profile for Plenty of Fish - here are my real-world guidelines. (remember, I don't do the whole "formula" thing)
Give some some insight - but don't over-share. I say you want to tell them what you're like, but don't give away so much information that there's nothing left to talk about over coffee. Say you like photography and you work in a restaurant - but save specifics for your dates.
Be honest. Using an older picture because you liked your hair better or you looked thinner is not a good idea. Use recent photos, and show off who you really are. Don't love your current job? Okay - but don't make up a job title, or use one from your past. If you're not crazy about what you do, laugh it off. My profile says something like, "I work to live; but I don't live to work," or "I'm a true 9-5er," to let people know that my job is something different from my hobbies.
Speaking of hobbies...
Have some. If you don't - get some. When the profile asks for your interests, you should have something to say other than, "Hanging out with friends and family." Remember when you were in high school and everyone told you to get extra-curricular activities for your college applications? Yeah, that.
Are you funny and sarcastic in real life? Then show that off in your profile Write like you would speak. If you're more serious or straight-forward, don't try to insert humor into your profile. You're setting expectations you can't meet - and attracting people who won't be a good match.
Remember, you can always update your profile. But it should be written about who you are; not who you think others will want you to be.