One note at a time and do it regular. There’s no quick way, just make it a part of your daily practice. You can do it with basic note practice but I think it’s best to just find a reason to search for notes and make it a part of your playing. For example, experiment and jam with scales in different keys, learn where the root notes are in each chord and regularly play chords in different places along the neck. The more you have to look for notes and actually use them – the quicker you will memorise them. That’s my opinion anyway.
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