Start by identifying the right policy
The easiest mistake is to mix up unilateral visa-free entry, mutual visa exemption agreements, and the 240-hour transit policy. They all sound similar, but the traveler profile and stay logic are different.
If your passport is covered by China's unilateral visa-free policy and you are simply coming for travel, planning is much easier. If you are connecting onward to a third country or region, the 240-hour transit option may be the relevant one.