When you develop the ability to sight read on the piano you'll be able to play more styles of music. To put it in simple terms, sight reading is the ability to properly play music you have never seen before.
Your sight reading piano practice should focus on things like checking time and key signatures, and keeping your eyes on the music. The time and effort you put in your practice will be well worth it as it will allow you to feel comfortable to play with little or no notice.
The first thing you should do is pick a piano method and use it to start learning how to recognize the notes. Starting with middle C you should try to learn the notes on the staff. Your focus should be on either the treble clef or bass clef.
When you become more advanced with your piano skills you can start using flash cards to drill note recognition. Your sight reading piano practice should also involve learning how to recognize intervals and note patterns.
Reading rhythms is important when it comes to sight reading so you should practice this to get better. Focus on learning how to play whole notes, potted half notes, half notes, quarter notes, and eighth notes. You should practice reading the rhythms by tapping or clapping and use rhythm flash cards.
To help you improve your site reading you should practice the scales and arpeggious in all major and minor keys until you have reached a good speed. Your site reading piano practice should also focus on practicing scales in octaves. Continue practicing the coordination between your eyes and fingers at least ten minutes each day to get better.
Every now and then you should play for a sing a long. This will give you some good experience and the opportunity to use your skills. After following some of these tips for a few weeks your site reading will get better.