I've been online dating for many years, and have met many wonderful people which have turned into long term relationships/friendships (and also my share of jerks). You tend to get a "feel" for who's BS'ing after a while. Listen to your own emotions and if someone sends up a "red flag" for you take it to heed, even if you dont know why. If something feels "off", it usually is. Keep your own emotions in check for a while as well as it's FAR too easy to get swept up in online romances that never make it off the computer screen. Good thing about those sites is you can block people that stress you out. So much easier to just block someone you dont like than trying to deal with a pushy admirer in person. LOL.
And when meeting someone for the first time, always keep a level head and some street smarts. If I'm going in their car I ALWAYS snap a pic of their licence plate and send it to my roomies, and give them a call or text a little bit into the date (even if I have my own car). If someone hesitates about you taking any type precautionary measures then that should be a big ole red flag warning.
There's some wonderful people in the online dating world, and one of the good things about it is even shy people can open up a bit about themselves online, and break the ice a bit before that initial nervewracking first date, but we do live in a crazy world with crazy people, so just stay smart and you'll do fine.
Using the more tame dating sites you should be fine anyways. I, personally, frequent some of the more specific sites for my particular interests (ok I'll admit it.. I like my guys kinky

) and haven't had any problems on those sites even meeting people with more extreme tastes. So on the vanilla, more Care Bear type sites... you should be golden
Happy dating!