Using the sustain pedal can make your playing sound a lot more grand and full sounding but in turn can also make your playing sound terrible if not used properly. It’s important to understand how the sustain pedal works to get an idea of where and when to use it. When you play a note on an acoustic piano it triggers a padded hammer which in turn strikes a string. Once the string has been struck a pad then rests on the string and mutes it to prevent the sound from continuing. Now when you press the the sustain pedal it lifts the muting pads away from the string so that once the string has been stuck the sound will ring on rather than muting it. Any of the notes I now play will all ring together in a lovely sustained sound. This is great when I’m playing one chord, but if I now play another chord without releasing the sustain pedal the notes of the new chord will bleed together with the old chord which can clash and sound wrong. The best technique is to lift the pedal as I leave my old chord and re-engage it once I’ve started my new chord. This will keep both chords separate and prevent any clashing. Try holding the sustain pedal down without releasing it, playing a load of notes to hear how bad it can sound. Then try pressing it and releasing it to see how it can be used to good effect.