The easiest place to cut is often the hasp on the locked door, through which the padlock’s steel shackle is looped. Hasps are usually thin and made of unhardened metal so – providing you can get a good grip – they often cut easily, enabling the shackle to slide out.
If the hasp is inaccessible and you have to cut the padlock itself, then go for the body of the lock. This is often made of brass, which is considerably softer than the hardened steel of the shackle loop (which may well damage the blades of your bolt cutter).