dapper(diaper)- if you can remember the diapers used for babies, should be kept neat and trim(spry).
DAPPER sounds like DATE PAR. How will you go on a DATE PAR?? Obviously by dressing well and being up-to-date. So Try to remember DAPPER as DATE PAR !!!!
dapper is very close to word DRAPER(Y).....SO drappery in your house is very neat and clean in its appearance.
For good marks you have to keep your exam paper dapper.
DAPPER = don + appear; don appearances is always neat & trimly.