Hi,
There is nothing particular. But it depends on your needs.
If for example you want the invoice numbers to start with a specific number, then you'll have to do something. If you don't care that it starts from the next number after your tests, then there is nothing to do on that end.
Same for the fake orders/users. You can potentially keep them on your HikaShop or remove them.
For example, on our website we kept the fake orders that we did since they are not taken into account any way for our accounting and they don't create any problem by being there.