You learn to read, by, well, reading. There aren't really any shortcuts. However, you should learn to recognize very common patterns, chords, scales, and arpeggios so that they're at your disposal when you need them. Make sure when reading that the melody stays intact, and then the bass (unless you're accompanying, in which case the left hand should be kept intact above all). If you're playing something extremely slow, you might take a pencil and go through the piece marking each beat, since the notation can get tricky. Leave out all grace notes, trill, ornamentation of any kind. And, obviously, improving your general technique will give you more tools for when you read. Look for repetition, a formal outline, and the roadmap. Make sure you know the time signature and the key signature, and make sure there's no funky stuff going on with the clefs. The best way to help your reading is to take a few seconds and look the piece over before touching the piano, so you can see any obstacles or little things you might miss on the fly.