The best way to prepare yourself is actually the machines that the courses will actually cover, dead or alive and download service manauls.
And actually get them working, this is exactly how I started in 2001.
At the time my dad worked at a computer auction house and back then LX and SX engines, LaserJet II/III and IIP/IIIP based printers were on the base pile when it came to printers,
And I obtained some SX and LX based printers for me to experiment on, these were dead printers, and I obtained a LaserJet II/III service manual from the auction house as well,
In 2002 is when I started on 1990s canon engines such as the EX and EXII, BX, AX, VX, and PX with work experience at a printer service company where I worked on a vareity of canon based engines that were being recycled at that that time, these were the classic canon engines.
In recent times since 2006 I started on the 4000, 2100, 2200 and 2400 series because these are the at the same spot as the SX engine now as it was in 2001.
In 2004, I started on Color LaserJets, with the 4500, and in 2009 I started learning the newer models 5500 Color LaserJet.
The oldest printer I am using that is in regluar service as of Jan 2010, is the BX engine LaserJet 4V.
My advice is to learn the standalone printers before moving to the multifunctions, because in most cases they use the same engines as the standalones, slightly diffrent but basiclly the same.
Example LaserJet 4345 is based on the LaserJet 4300 engine, and the M3027 and the M3035 is based on the P3005 engine.
