TIP for the colors of the keys:
1. print color tabs (Word eg. Find matching colors with those of the method)
2. cut according to the width / length keys
3. laminated. Personally, I took good plastic sticker to cover school books.
4. fixing with "dough fix". Be careful not to get between the keys ...
That way, the tabs do not interfere with experienced players. And one can always remove and replace them if necessary!
Good luck to all beginners! Be persistent and inventive!