Hi and welcome,
I made a pattern first and then used thick fabric as a mock up, before I cut into my leather. I also used snap clips around the back.
My hair ties where sewn on, after a year I wanted to tidy up the wig, found Velcro worked well, little bit fiddley to sew on, but works really well.
Also after a year fighting with my hood, I placed a black snap clip on the top of my leather head piece well hidden, and hand sewn 2 on my hood, one is so hood sits above eyes or below. Best thing I ever did. The hood is doubled so hand sewing you cannot see.
Test quite a few different types of mediums for your red outline, I used paint...tried fabric, sticker and ribbon....I did a crap job on those.
Good lick