the lighting at the party will be kinda like at a hotel lobby..
the party will be held at an evening in a restaurant inside a hotel..
my sister not really has a preference, but i think that natural light is better, isn't it??
i've just bought my cam for two months, and i've never done this type of photoshot, i usually take photos at the morning or afternoon when sun is shining bright, so kinda blank for the settings and equipments..
thx anyway for the replied guys..
If you are at home now, turn on your lights, try shooting something at ISO 200, f2.8, aperture priority. (I am not suggesting you can only use aperture priority, i just wanna minimize the parameters to let you see the result)
Try and see if you are getting blur shots handheld.
Then slowly go for smaller aperture, like f5.6, f8 and see what happen.
Most likely you will have blur shots.
This is when your ISO is useful. Increase your ISO slowly to 400, 800 or as DM mentioned, it can go to ISO 6400 with pretty clean shots (except the dark areas where you will see some noise).
But then, as ISO increase, noise increase. So it depends on whether if you (or your sis if she has high expectation) are satisfied with the result.
You mentioned the shoot is in the evening in a hotel. So the light will be less as the event progress into the night right? This is when you will need more lights.
A flash will also help to freeze motion. You may not want all photos to have your subject posed (static) and blurred motion of other people moving around in the surrounding.
I suggest you get a flash. And more rechargeable batteries if you shoot a lot.
As for tripod, unless you want to be in the shot and don't want others (such as waiter or waitress) to help you take the photo, you can leave it at home.