"Start over... go back to the beginning... try again..." These are all phrases I heard a lot during lessons and practice. Whenever I made a mistake, I was reminded to at least go back to the beginning of that measure and play it again. This is actually the fourth tip for better piano practice!
Though it may seem repetitive, going back to the beginning of a measure or bar when you make a mistake actually saves you time and effort! The reason is simple. When you make a mistake and continue on past it, you have subconsciously affirmed to your brain that it is actually the right note.
Instead, if when you play the incorrect note, try stopping there and going back to the beginning of the measure. This corrects the note and helps you remember the correct one instead. This saves time and effort because you haven't learned a mistake that you have to take the time to correct.
If you have happen to have learned an incorrect note and habitually make the same mistake when you play a song, it will take just a little more effort to correct. When you make the mistake, go back the beginning of the measure and play the measure with the correct note. But don't just go through it once! Play the measure over and over until it starts to become natural and easy. Then, go to the beginning of the bar or page, and play through until you get to the note. If you play the mistake again, you know you have a little more work to do. If you play the correct note, congratulations! You've fixed your mistake!
Now, if you come back to the song later after fixing the mistake, don't fret. It's quite common! Just continue to play through the measure or bar over and over until it is completely fixed. As you continue each day to practice the measure, you will be less and less likely to play the mistake later.
To conclude, if you make a mistake while playing a song, make sure to start the measure over to prevent future headaches in practice!
Read the whole series, "5 Tips for Better Piano Practice", here