In many ways, women are people too.
For some reason, when you are single and desperate, they smell it on you like a dog smells fear. The key is to relax and get comfortable with yourself first. Few things are as unattractive as insecurity in a man. The next is not to jump the gun, if you put too much pressure on a girl or yourself that it must lead to marriage it may very well scare them off.
Another point is don't expect miss perfect to come knocking at your door, if you don't go places to meet people, you can't meet people. If you are uncomfortable going out, try some internet chatting or date sites, wherever you go, remember not to lay it on too thick and if you fail learn from it and try again. There are very many lonely people out there, eventually you will find the right one.