It takes courage to ask... for anything.
With that in mind I'd like to make this suggestion, when you are considering asking for anything — in your job, or your personal life — Ask for what you want; NOT what you think you can get.
You never know what the recipient of the request is thinking so it is in your best interest to ask for exactly what you want up front... even if it seems out of the realm of possibility. When you ask for what you want you set the stage for clear negotiations, letting everyone know exactly what your expectations are up front.
When you ask for what you think you can get, you sell yourself short — bargaining with an imaginary opponent and ultimately not satisfying your original intention.
Nobody wants to go to the well twice — give the recipient of the ask the opportunity to evaluate what you really want and you may be surprised by the result.