Learning how to upgrade AEG internals?

I would like to learn how to upgrade/repair/clean an aeg gearbox. Can anyone point me in the right direction to start learning how to do this? For me, personally, the best way to learn is to do it hands on. So should I buy a gun like this:
http://www.airsoftgi.com/product_info.php?cPath=139_24_150&products_id=2108
and just study the internals and such? Maybe even try upgrading it once I get the hang of things?
Thanks in advance,
Mike