If they look too good to be true, then they probably are
In other words, if their photo looks as if it's been taken on a professional photo shoot for Topshop, then it's more than likely a fake! Despite the wide availability of photo editing tools like Photoshop, many people still believe in these unblemished and refined photos. However I would advise that you ask for other less professional pictures. If you don't get one, move on. With the majority of people being members on Facebook, Twitter etc., there should be no excuse for someone not to send you a more amateurish looking photo.
As shallow as this sounds, online dating is by its very nature one big shallow goldfish bowl. In the main, you are judging and being judged on your appearance. Accept that not everyone is going to respond to you, just as you will not respond to everyone who initiates contact with you. In other words, try not to take the rejection that invariably comes with online dating too seriously. If, like myself, you find this hard to do, then I would suggest that you search for new ways of meeting someone.
Pay attention to the usernames
This can reveal a lot about the type of person that they are/what they are looking for on the site. For example, if you have just come out of a relationship with someone who had cheated on you, then you may want to think twice about responding to a user who calls themselves 'womanizer 101'!
Smoke them out
In other words, suggest meeting sooner rather than later. Not only can three days of exchanging messages not compete with two minutes of face to face conversation with someone in terms of seeing if you have a spark and if you actually like the person's personality, suggesting a meeting early on in your contact will result in less of your time being wasted/your hopes building. After all, if they are only interested in receiving some virtual attention then you can move on to the next person.
Be wary of private photos
If a user has a stack of private photos, I would be wary. Maybe they really are just pictures of the user with members of their family/friends that they don't want just anyone viewing; however the pictures are more than likely to be of a Marvin Gaye sexy variety. Fair enough if you're just looking for some fun or casual dating, but if you're interested in a relationship, I'd steer clear.
Limit your online usage
If you are finding yourself perusing the profiles of hot girls/guys while at the freezer section of SuperValu (ahem), take a breather. Trust me, checking every ten minutes to see if your latest crush has responded will only result in stress and frustration, especially if you see that they have been online yet not responded to you. Helpful hint: avoid downloading the app for easy access to said website. Not only will it increase your usage, it may also use up extra data on your phone.
Finally, trust your gut
If the messages someone sends you, make you feel in any way uncomfortable, or if you feel that the things they are saying just don't add up, trust your gut feeling and put a stop to the communication.