Sight-reading piano music is much like learning how to read a new language. It takes a lot of practice but you will experience greater success by avoiding these 4 common piano sight-reading mistakes.
One mistake I see over and over again with my students is that they look down at their hands instead of at the piano sheet music while they are playing. Sight-reading requires that you don’t stop or pause but continue with a steady pulse so this common mistake can cause you to break that steady tempo as you look up to find your place in the music again. Because the music won’t stop or pause in the Piano Marvel sight-reading assessment (SASR), this can help you make sure not to look down at your hands so you don’t lose your place.
Another mistake I see (and sometimes make myself!) is not looking over the music before you begin to read the music. You should be looking to see what the key signature and time signature are. Do they change anywhere in the music? Are there any repeating patterns or tricky passages for you to look at before you begin? Look at the symbols to get an idea of how the music is supposed to sound including tempo, articulations, dynamics, and clefs, for example. Looking over the music can give you a "feel" for how the music is supposed to go or sound. The SASR gives you 20 seconds to look over the music before the piece begins, to encourage this helpful practice.
It is natural to want to fix mistakes when you are reading piano music. One defining characteristic of sight-reading music, though, is to keep a steady tempo. I had a choir director who said “If you’re singing [in this case playing] the right note at the wrong time, it is a wrong note”. Because the SASR plays straight through at a steady tempo without stopping you get a lower score for playing the "right note at the wrong time" so this also reinforces not fixing your notes when sight-reading.
Just like learning to read words, learning to read music takes a lot of practice to get good at it. One common mistake is simply just not sight-reading often enough. In order to be more fluent and expressive in sight-reading music, it is good to make sight-reading a daily habit. Piano Marvel is the best and most effective sight-reading tool that I have been able to find and provides ample opportunities for sight-reading including the SASR, Sight-Reading Samurai, Monthly Challenges, and thousands of songs in the Library to help you develop this skill.