my 2 cents

Make two of them.

a sub 1000 $ with at least one nvidia (1060 6GB) and one amd ( rx 470 8 gb) card and mobo used, windows   
and the good one with the rest

For the good one: no more than 6 card, use simplemining, the best card value/ hash if you are able to find them, are the 3060ti.
The boxes need to remain intact as well as the bios in case you will decide to stop mining it will be easier to sell them , a 1.3 kw PSU with plenti of 8 connector ( at least 12 PCI 6+2)

With the first rig you will be able to learn software and also try  the different strategy. For example you know that today with one single rx 580 I was mining ERGO more profitable than eth ?

The good one hopefully will teach you to make calculation, understand roi, understand that few MHs make the difference and few degrees on the memories may break the cards etc and that 24/7 mining its boring but its profitable ( at Least now)
oh, and don't forget that in some countries you are supposed to pay taxes on the revenues...