Gti black waist trim paint finish

Hi all,
I'm going to attempt to refresh my waist trims. They are a little tatty, paint missing in places and the aluminium has reacted in these areas.
Can anyone give me pointers with the paint finish, the texture is uneven. Is there a specific process needed to achieve this.

TIA.

Flat with p240 or p320
Degrease
1 light coat of acid etch primer, 20 mins flash off
2 - 3 coats of satin black

That's what I would do, I wouldn't worry about trying to achieve a crinkle finish