I usually have a hard time getting past: A) The people who (in text) begin with "asl?" because they use the site when they get horny, not when they want to have an actual conversation B) The (video chat) exhibitionists who start the conversation with their dick in their hands. Although I do have to admit I've had maybe one or two good conversations on that site.
The best way to avert or rather, make the first one less frequent, is to use the tags and append Conversation to it. This usually helps filter it for me.
Last time I was on Omegle I don't remember them having that feature, but I just checked it out and it looks intriguing. Unfortunately, when I typed conversation I got the message that Omegle couldn't find anyone with the same interests, but still that feature might finally make that website worth using!