From the time you sign up for a service through the time you meet on a date, it's important to be safe. Read Online Dating Magazine's Online Dating Safety Tips article for specific things you should and shouldn't do. In a nutshell: never give out too much personal information; never give a home phone number; always meet in a public place for the first date; ask for a recent photo (or how old posted photos are); and trust your gut instinct. Read the article for more safety tips and full descriptions.
Your profile is one of the two key elements that will determine if a person emails you on an online dating service (the other is photo - see next tip). Thus it's important to make sure that your profile is lively, fun, and positive. Avoid negatives (I'm lonely, I can't believe I'm doing this) at all costs. Examine other profiles and determine what about it makes you more interested or less interested. Read Online Dating Magazine's Profile Tips article for more advice. If a person finds your profile interesting and not generic then you have increased your chances of someone showing interest in you. Make yours interesting!
Face it - when doing a search on an online dating service the first thing that grabs your attention is the photo. This is the single most important