Most polarizers are in a rotating mount so that you can rotate them on the lens and see the effect.
It can help if you put a small piece of tape, white paint/white nail polish on the outside, rotating ring.
That way, you can take the filter, hold it to your eye and see the effect. Note where the white mark is located, then when you put the filter on the lens, place the white mark where it was when you looked through it. If you move, look through the filter again!
Don't forget too that polarizers carry a 2 stop penalty in exposure. That means if you are using apature priority camera, you lose shutter speed. If anything's moving, well it could blur. If you have shutter priority, then you lose depth. The key might be to increase your digital film speed if you can.