You may not like this :-)
You have to decide what you are looking for first - friendship, dating, LTR, sex. Then you have to remember that there are likely to be a lot more men on those sites than women - which means you have to give any women you contact the impression that you're a nice guy who is worth getting to know either on line or ideally in real life. Oh and given the kind of ratios on such sites, you need to be prepared for the women to say "thanks but no thanks" and move on without letting the rejection get to you.
Now for the not so good bit. From what I've seen of the questions you've asked, I'd say you are generally down on yourself and your looks, a bit self concious, far from light-hearted and maybe verging on depression. If you come across like that when chatting to women on line, or in real life for that matter, they are going to exit, stage left, with the amazing speed.
And if you think that things like that don't come across when you are chatting to people on line, you're wrong. I've been chatting to people on line for a very long time, and though I'm not the most perceptive of people even I can almost always pick up on when someone is down or has some kind of problem they want to talk about or simply needs to let off steam.
Go see your doc, a counsellor/psychotherapist/whoever, get to know yourself and to come to terms with who and what you are so you feel comfortable in your skin. After that, the rest will come