I am in the process of doing the same.
This web site, esp the "Instant Recognition" essay has been invaluable in the process: http://www.themorsecrusade.g5fz.co.uk/
I am using a variety of methods :
on the air QSO's,
the Koch CW trainer http://www.g4fon.net/
QRQ is nice for helping with instant recognition--I write my own single letter files for it (easy to do) http://fkurz.net/ham/qrq.html
Also, here is an excellent article: http://www.morsecode.nl/20wpm.PDF
Good luck and work hard each day!