I’ve made about twenty cloth components, vast majority being capes/cloaks. The process will obviously vary depending on the stature of the MOC, and what kind of cloth piece you’re wanting to make. What I do isn’t very scientific, I really just start with a large piece of cloth, drape it on my MOC in a way that is roughly what I want it to be. Make cuts based on that, and then do any sewing on additional clipping necessary. You won’t always have to sew things if that’s not your cup of tea, but than you will need to be more precise.
On this MOC, I used a tactic which gives off a very closed up cloak look. Basically, take a square/rectangular piece of cloth, line it up with the middle of your MOC on their back side, fold each side over so it’s resting on the front side of the MOC. You should have excess cloth that goes over the shoulders both front and back. Fold that either all back, or onto the shoulder on top of each other, and then sew it down. If you want, you can turn it inside out at this point, and there shouldn’t be any threads sticking out.
Alternatively, you can try and do a more classic cape, which I have a tutorial on for when I did my Tuyet MOC.
If anything is unclear, or you have other questions, I would be more than glad to answer it. I always want to see more custom cloth used for Bionicle.
Edit: Tuyet topic link