The first thing you have to consider seriously is the selection of the piece(s) in your program. i.e. repertoire. Certainly you should choose what you love to play according to our ability. Students should play the early works of a composer first before tackling those late compositions. By this we can understand the stylistic development of that composer better and thus build up our skills on both technical and musical aspects gradually. Teachers should also expose their students to the lesser-known masterpieces but not just bound to those frequently played ones. Works like those by Rameau, Couperin, Hummel, Dussek and John Field are only handful ones of the vast field of the rarely-performed yet precious masterworks.
For the works you play in the concert or a diploma level exam, a clear and structural planning for that every particular piece should be worked out as early as possible. This should include the division of each section, the places for breathing, the ways of phrasing, the dynamic and emotional contrast, the specific fingering and so on. This helps to better understand the meaning in the music and improve your memorization too.
Daily technical exercises are extremely crucial as they form the technical basis of any single composition. Students should thus include some basic exercises to warm up well before they practice the pieces. The most basic ones can be scales, arpeggios and octaves; particular études like Chopin’s embrace both technical and musical demands. You can also make up some exercises from the pieces you are working on as well. These surely are useful for students to firmly establish their techniques for what they are going to perform in a recital or an exam.
Another aspect of being well prepared refers to solving the problem of memorization that most students are worried about. Many are afraid of memory slip during a concert or an exam. To avoid such problem, the way to memorize a piece is of utmost importance. Of course some of you are more gifted in memorizing a composition naturally, but still there are means to improve your memory. Some students are used to play a piece hundreds to even thousands of times to confirm that they know it really well, but this may not be enough. Studying the score visually without playing on the instrument is one way to affirm your memory of that piece. In fact, this not only helps with your memorization, but also other aspects of the music such as the dynamic contrast, the color or the tone of a particular phrase, the overall structure of the piece etc. Another way is to be able to listen to the whole piece from the beginning to the end play back in your head only without actually playing on the piano. This can definitely ensure the security of your memorization of the piece.