My own experience of online dating wasn't that positive and found that I seemed to only attract the type of man that if I met them in the street, I would have given them a wide berth!
One guy I did keep in contact with and actually had a few dates with , blew very hot and cold - there seems to be a general thing with some men that if you are on a dating site, you must be desperate! With this guy, after the 3rd date, he tried to insist that as he had seen me more than once, he had the right to have sex but only at my place. Difficult, as a single parent, I was living with my parents!
I found out several weeks later, after he had a dated a friend, that he was actually married and his wife was pregnant! He told my friend that using dating websites worked out cheaper than seeing a prostitute!!!
I was just unlucky - another friend has just got married, after meeting her husband on a dating site.
I'd just say to go in with an open mind, you may not meet anyone that looks like the ads on tv, and be careful if you meet them - have someone either in the vicinity or easily contactable and whatever story they tell, don't give them any money for any reason !