What kind of film stock u use for practising is just a question of what u want to do with it. If u want to practise how to correctly expose film u'd better take reversal stock, because reversal stock has a smaller latitude. This means u can't just under oder overexpose without even noticing because you will see if anything is under- or overexposed. With negative film, if it's not real bad, it'd be no problem to fix it - using reversal u can't fix it in the DI anymore. But if u just want to practise how to expose film I suggest u do that by taking stills - much easier and cheaper and enough for what u need.
If you wanna shoot a real film it depends on what look u wanna create - there can't be any rule on what film stock is best - there are many different because there are different cinematograohers, tastes and tasks they have to suit. Most feature films today are shot on negative film, but just get some rolls of different film stocks to play with and try what u like or what u need. As far as I know there are only daylight reversal films available from Kodak but u can compansate for that with a filter - or u could shoot black and white what gives u a very interesting look especially on reversal film, too. If u decide to shoot outside there'll be more than enough light to go with reversal film. So - just try some different stuff and experiment.
U can purchase film on ebay but got to be careful. Especially when using old color film stock of any sort it's quite likely that a color shift has been going on. If it's not too bad u can fix that in the DI. Also u have to be careful because the light sensitivity of the film decreases with time and u need to compensate for that - after a few years this can easily be 1-2 stops. So if get film on ebay u should carefully test each roll. But if you just want to shoot some feet of 16mm - call Kodak and beg for a free roll or a recan- it's quite likely they'll give u one, and if not, at least a good discount. Most of the times Kodak people are real nice :wink:
