What make/ brand of OAG are you using?
The previous comments are pretty sound; to make it a bit easier to orientate and understand field movements, position the guide eyepiece in either dec or RA, that way you can move from the object in the centre of the FOV to the prism with only one movement of the scope.
The pick-off prism doesn't give a wide FOV, but usually ( well, sometimes!) there's a star to use.
Focusing is an issue: I need either a prism diagonal or a 2" extension in the guide train.
There's a neat little "virtual star" program available which allows to to practise guiding indoors
http://sweiller.free.fr/SGE/SGE-star...g-emulator.htm
I've used it on my HEQ5pro + QHY5 with PHD.....
I'm playing with a Vixen clone 50/50 beamsplitter for guiding; you get a 100% field as per the camera, albeit with a slight loss of light.