I don't know if you are asking from the point of an IA or owner, so I will give you an idea of both.
As an IA, you know what systems and items need to be inspected, and have access to the shop manuals as well as IPCs, ICAs, and other service information, so it is relatively simple to find the parts in the IPCs such as gaskets, filters, types of lubricants.
As an owner looking to assist, I strongly suggest you consult with your shop. Many properly equipped shops already have the necessary items on-hand to perform the tasks, and very likely would take offense to the customer brining in their own parts and consumables. If this is the case, please have a talk with your IA to determine what they expect. You certainly don't want to get off on the wrong foot by 'bringing your own steak to the restaurant'!