[TomVDB]

What do you want to do with it?

“Starting” is a bit ambiguous.

But I suggest that you first simple read the ISA specification. It’s surprisingly readable and if contains justifications for some design decisions.

After that, buy a small FPGA board and run a picorv32 CPU in it. Or one of the many other RISC-V soft cores.

[eternal_virgin]

Ah, I'm mostly hoping to learn how it works and what I can do with it. Trying to find a hardware-based pet project!

[TomVDB]

Buy yourself a TinyFPGA BX.

It’s a small (tiny!) FPGA board that’s still large enough to run a RISC-V CPU. It’s a full open source flow. And there are plenty of examples.

Get that first LED blinking!

[dancek]

Or an UPduino which is still cheaper. I've had good experiences with one, though I'm only at the "PWM-animated LED" stage right now.

Oh, and https://www.nand2tetris.org is great. You implement a simple CPU, and though the language isn't a real-world one you learn enough to probably be able to implement a similar CPU on an FPGA using VHDL or Verilog.