If you can work in manual, work in manual, if not then Av as said is best. Start at iso 1600 and see what shutter speed you get. If it is too low (and remember the golden rule shutter speed = length of your lens plus one) then you may end up shooting at 3200. Shoot, check review repeat.
Remember it is better to have a sharp shot that is noisy than a blurred shot that is clear of noise.