The great thing about this costume is you can make it however you want!
I went the route of shorts instead of pants, boots instead of shoes (only because I remembered I had them and aside from Halloween or maybe a punk show, I never really wear them), and, I have opted out of the cape because I do not have enough yellow and/or black material, and I feel something knit or crochet would get a little bulky.
In the end, it's up to you how you want the final look to be.
Also, I apologize for some of the pictures; they aren't what they could have been, and it's pretty hard doing everything yourself
-Red Shirt and sleeves from a Green Shirt
-Sewing Needle & Thread OR Sewing Machine, Thread, Bobbins
(these will be used to attach Green Sleeves to Red Shirt)
-Piece of Elastic for Mask
-Size G/6 (4.25MM) [for making the mask]
-Size K/10.5 (6.50MM) [for making the belt]
Step 1: The Mask
-Ch. 21 and Slip Stitch into the First Stitch
-Ch. 23 and Slip Stitch into 21st chain from hook
(this leaves 2 stitches open to cross the bridge of the nose)
-S.C. into each of the two middle stitches
-S.C. (32) into eye loop
-S.C. (2) in the middle
-S.C. (32) into other eye loop
-S.C. (2) into the middle
-*S.C. (5), EX.S.C. (4), S.C. (5);* [repeat once more], S.C. (4)
-DEC^2 over the middle
-*S.C. (5), EX.S.C. (4), S.C. (5);* [repeat once more], S.C. (3)
-Slip Stitch & F/O
Step 2: The Belt
You actually don't have to take measurements; you can just simply start chaining and end where you'd like
-Ch. 100, SL.-ST. to form ring
-[(3)B.P.-D.C, (2)F.P.-D.C.](20) = 
-REPEAT previous step until desired width.
Step 3: The Shirt
If you have a green shirt with sleeves, remove them as well. Once finished, you can skip ahead to pinning the green sleeves to the red shirt and proceed to sew as normal.
However, in the case where you have taken your only green shirt and turned it into a tank because of the heat this past summer, then you will need to make some sleeves.
Details are listed on each picture below: