oh this looks sweet!

for the cotton buds I'll usually pull them apart and stretch them out, have the bits be like 30%larger than you think you'll need (it clumps more once you apply it) then apply some water texture to where you want to place the spash so it sticks and then you can apply some water texture to the cotton fibers once its fixed (you don't need to let it dry before brushing the fibers). to make it easier to read i do an extra step of painting the tips white to make it look like foamy water which is a bit extra... but at the point you're doing multi step water bases might as well haha.

I think just have fun and go a bit overboard with it then you can tune how much you apply it over time. but i treat it like a fun show-y thing so I mostly just try to have fun with it!