Read through the music slowly. Very few people possess the skill or talent to sit down at the piano and immediately play a piece of this caliber at the correct tempo. Reading through the piece slowly will help you see how it is constructed and show you what aspects of it you will need to practice.
Break the music down into parts. Playing the piece from beginning to end, over and over, will not necessarily make you any better. Start by playing the first phrase of the music. Play it once, and then play through it about fifty more times. It may not be fun, but it is what it takes to learn a piece. If there are just a couple of measures that are causing you difficulties, play those measures until you cannot play them incorrectly.
Play the entire piece at a slow tempo. You will not get all of the notes under your fingers by beginning to play the piece as fast as you possibly can. Set your metronome at a low speed, and determine the fingerings that work best for you. Once you can play a section perfectly at a slow speed, then you can bump the metronome up a notch. Repeat this process until you reach the tempo at which Mozart marked the piece.
Once you can play all the notes relatively well, focus on the dynamics and articulation. Notice each staccato (abrupt) and legato (smooth) marking. Try to refine and polish your performance as much as possible.
In most pieces you play, particularly at this level, there will be passages that prove difficult. Sometimes, though, what appears to be difficult at first will become much easier with practice. Work through all of these issues. Repetition is very important to getting the kinks out of your performance and achieving accuracy.