1. Include a .capx file of your project. This way we can see what you're actually doing in your project. It saves us from asking "have you done this?... have you done that?" - we can just see for ourselves. Need a place to host files? Try Dropbox. (Remember to put it in the Public folder.)
2. Don't say "it doesn't work" - tell us what happened. If you say "it doesn't work", the first question we'll ask will probably be "what did happen?". You can get your question answered quicker if you include a good description of what actually happened. Don't forget to tell us what you expected to happen as well - it may seem obvious to you but it often isn't to us!
3. Include any error messages. You don't have to take a screenshot - Ctrl+C and Ctrl+V lets you copy and paste a message box's text to the forum. If you say "I got an error", the first question we'll ask will probably be "what was the error message?". Often the text of the error message is what allows us to solve the problem. So don't forget to include it!
Bear these things in mind, and your problem can usually be solved in half as many posts :)