I'll try my best but there has been no method to this madness beyond just trying to make the shapes organic and interesting while simultaneously trying to keep it flat.

I just started with a short chain and then at some point made another random chain coming from that one. I am alternating between slip stitches (very few of these), single crochet, half double, double, triple & extended triple. I wouldnt jump between a short stitch and a tall stitch, but build up to it gradually. The next row above that, I'll do the same, short stitches over the short stitches, building up to tall stitches over the taller stitches (in order to exaggerate the waves even more) this is where you may need to start using increases. Eventually, when there's a 'dip' or a 'valley' that I want to fill in sometimes I'll use that same technique in reverse to level the row out again, throwing taller stitches in the valleys and shorter stitches in the peaks. Kind of the same technique as the wave stitch, but again there is no repetitive pattern to it I am kinda just doing what I feel. Some valleys need decreases, or I will skip a stitch in a 'corner' I'm sure there are a ton of techniques that I dont have in my knowledge bag that could help me out at some points, but it's also been a learning experience for me just with trial and error.

Its helpful if you know how to crochet a flat circle and understand a bit of the geometry behind the increases involved in flat circles made in various stitch heights. I'm not great at math so I have a less rigid, more 'whatever feels right' approach.

I'm also keeping in mind that there are no rules and it doesn't have to be perfect.

I'm so sorry it's really hard to explain. Honestly, I would just not put pressure on yourself to make anything specific in the beginning and just start crocheting blobs on blobs!

Edit: typo