First off you'll have to learn your notes, so get a beginners book that takes you through from very easy two and three note pieces right up to using two hands, then once you know how to read music you can start incorporating some of the techniques that I'm about to go over.
No.1
Never look away.
Never look away from the page that you are reading, unless you have to do a big leap where you have to look at the keyboard in order to hit the right notes. If you look away from the page too much you'll find that you'll loose your place more often and find it much harder to focus mentally and probably with your eyes too.
No.2
Read ahead.
In the beginning when you're learning how to read music for piano, you'll probably find it hard enough playing the notes note for note but as you progress you should try and read ahead, at first one or two notes ahead and then as you progress try and get it so that you're reading a bar ahead, it's good to practice this technique with songs that you're familiar with. When you come to a part of the song that's a bit more difficult, having that extra second or so to prepare really does come in handy.
No.3
Scales and chords.
When you get to more difficult pieces you'll find that it's almost impossible to read every note, that's where your scales and chords come in, if you see a big run of notes and you know what scale you're in then all you have to do is look at the first and last notes, then it's just a matter of playing from the first note to the last in that particular scale.
It's the same with the chords, if you know the patterns and the key signature then you don't have to look at all four notes in the chord, you just have to look at the note that you're most comfortable with and then play the chord from that note.
No.4
Know Your Key Signatures.
If you don't know your key signatures then you'll never be able to master tip No.3 The best way to practice your key signatures is to play in as many as you can, going over and over them, when you're away from the piano, practice saying them out allowed, for example the key signature of E would be F# C# G# D#.
Learning how to read music for piano can be fun, but it can also be really frustrating and strenuous so make sure you only do it for a short amount of time in the beginning, maybe half an hour and then as you get more comfortable with it you'll find that you can concentrate for longer.