When it comes to asking questions, I consider myself a bit of an expert. I ask thousands of questions every week, and I usually get an answer, too. Despite all of the details reagrding how to ask a question, the most important bit is to just ask the question. Until you vocalize it, no one will know that you need an answer. Even if your question isn't well formulated, a good problem solver will begin cross-examining your question. Of course, it is always good manners to have attempted researching your question before asking it. Showing that you truly have interest in learning is always going to create a better environment for question answering.
Context is always important for communication of any type. If you've researched your question, and either found nothing (or at least nothing you understand yet), make sure to include what you've tried and what you suspect the answer will look like. The more information you can provide the easier it will be for someone else to come to a conclusion that suits you. If you have any sample code that you want others to look at, include it, but make sure to give it context. Remember that the people answering your question haven't been slaving over it for the last few hours, days, weeks, so they will need details. Often times its best to post fully functional (or nonfunctional as the case may be) code instead of a snippet. That way other coders can actually run it on the command line and get a result. Just looking at enigmatic variables and calls to unavailable databases won't do them, or you, much good.
Another important facet of question asking is how you ask. Always remember to be polite and humble. The people that are answering your questions are generally doing so out of a sense of community and general kindness. No one has to help you. It is only through garnering the kindness of others that you'll find help (unless you have tons of money to throw at the problem). Something that falls under this kind of courtesy is checking back regularly for your answer. Sometimes you haven't included information, or the community needs further explanation in order to help. Also, if you come up with an answer before the community you should update the thread or people with the answer you discovered.
In the end, just ask your questions, and if you don't get the answer you need, ask your question again, in a different way. If that doesn't work, ask it somewhere else. Someone out there has the answer, because if no one has the answer, then you just found a new app idea.