Some sleeves just have a bit more to it than just a plain straight forward sleeve.
Give it a try really interesting and very nicely designed sleeve.
Cut out sleeve, Add seam and hem allowances
Cut facings and interfacing for cuff section.
Mark all notches.
Mark seam allowances.
Mark dart and opening section.
Back of sleeve, with cuff plus iron-on interfacing -
placed right sides together on sleeve
Sew from side on hemline,
up on placket, horizontal at bottom of dart
down on placket. to other side of hemline to side seam.
Cut open placket section and into corners.
Press seams open.
Grade seams smaller and corners off at hemlime.
Turn facing and poke corners out.
Press seams flat.
Pin and sew dart
Press dart flat. I like pressing to both sides
where there is lot of fabric and facing