Get Better At Playing The Piano

First, you have to be aware of the fact that playing the piano is not easy. It is complex matter.
You have to be able to devote a certain amount of time, depending of your aim - do you want to be amateur, semi-professional or professional pianist? For amateur I think 2 hours daily are enough, for semi-professional at least 4 hours daily and for professional you should practice every day minimum 6 hours daily.
However, a lot of musicians and people omit one very important thing about practice and it is: You have to be concentrated and devoted to music, not just only play because of the playing. If you do not have an aim what do you want to improve in a certain piece or tune, then 16 hours will not be enough. You have to love what you do.
The practice very depends on the style you want to play and the piece. But in general, you should practice arpeggios, scales, chords, octaves, thirds and sexths as scales and trills.