Try mining with the CPU of your PC. That's how I started. It cost me nothing to use the PC, I already had.
No it cost you in a depreciation of your computer and electricity consumption. And it is a pain to mine on home PC in 2019. Please don't mock your PC
Well, of course it won't be profitable. But it is a cheap way to learn and get knowledge required to start properly.
Best advice is usually: Google and read about it, play a bit with your CPU and setup some altcoin miner before you should even think about going bigger and potentially invest hundreds of $ in (specialized) hardware.
In case you already have a suitable GPU in your PC: Give that also a go.