Thanks for the love, peeps (even the great at ripping off comment :) ) - Supernintendo Chalmers is definitely right, I just do mine for myself and wanted initially to copy one of my fave card designs from when I collected... by no means am I pushing for them to be used as anything official, it's just good to be able to use my own shots from games I attend and have them printed up and signed by the players... It's not like I'm an ad agency making money off a talented designer who does it professionally :)
Indominous-Rex hit me up on twitter if you want any advice on getting them printed (card size, prepping, who can print them, rough cost), otherwise, if you're just doing them for yourself, I'd just google some ideas and try to use them as inspiration... There are quite a few card collecting websites out there that actually allow people to sell their cards, and they are really good to sort by year and sport and brand...
If you find it a bit tricky, stick with it, it's really rewarding to get the finished product and get it signed if you get to games... It was great to get Rusty Hinder to sign one I did of him at his last professional game and have him say that after all his years in the NBL he'd never had a card...