1. There's no definite amount of time for practicing. It's different for everyone. Generally, your practicing time should be long enough that you can go through all your pieces and fix the bad spots, and not so long as to cause high levels of pain. For ergonomic reasons, your average practice session probably should nor last more than 3 hours.
2. Start with technique: scales, chords, Arpeggios, etc. It is good warm up and prepares you for your pieces.
3. Always listen to yourself when you're practicing and don't get distracted. Think about interpretation as well as technique. Ask yourself: what more do I have to offer for the music? What needs more work on? What is the composer trying to tell us?
4. Listen to famous pianists on recordings and write down what they do at certain places for the pieces that you are working on. You don't have to copy what they do but it will make you notice things.
