Some actors/directors may well disagree with some (or all!) of this, but if you are not particularly experienced as a screen actor it may be worth considering:
If you feel that a scene or take has gone badly for you, ask them if you can do it again. Very often, in my experience, inexperienced student film makers don't really know much about acting (or actors) and sometimes don't even watch the acting because they are so concerned with everything else! A professional/experienced director would spot some duff acting and ask you to do it again anyway, if there's time (sometimes there isn't, and they're stuck with a scene with dodgy acting in it - we've all seen them and I've been in some of them

).
You may find that they don't mind you looking at the footage before they move on to the next shot - it's easy enough to do these days. if you are unsure about how a scene went
for you, it's probably worth asking - though obviously it would be very annoying if you asked after every take! A director will often look over the scene /take before they move on to make sure he/she has the coverage they need in any case and they may not mind if you look over their shoulder. If they are relatively inexperienced you may find that they don't look at the acting at all - they just look at all the difficult technical stuff they are learning about! It's certainly the case that many student directors have no idea how to direct actors. If you get a chance to look at it, you may feel very strongly that you could do better, in which case you can ask if you can do it again. If they don't have time, or they are really happy with it, you may have to move on - but it's worth asking. It's more difficult (sometimes totally inappropriate) to do this on a busy professional shoot, definitely don't ask to do this on any kind of TV soap, there really won't be time for it - you can be
very unpopular if you hold things up. It can also look a bit insecure, especially if you don't have a big role or have never had any kind of conversation with the director,
but on a student production, where you are volunteering and helping them out, you need to get something out of it too, because I don't suppose you are getting paid! Getting the chance to see how you come across before the film is edited can be very helpful.
Don't be afraid to ask questions or voice any major concerns - especially about safety - it's usually possible to do this without hurting anyone's feelings or looking like a prima donna. They are learning and you may be able to help them get a better result, you will almost certainly know more about acting than they do, even if you don't know as much about filming.
Get a written commitment about the footage and get the name and contact details of their tutor before you start. Sadly, getting footage from student films often turns out to be really difficult. Be professional but firm!