For me, the collar was The hardest part!
I used a bucket of gumpaste since it was the same dimension I needed to get the nice curve.
I rolled the fondant & cut it about 4" wide. I needed about 19" in length. I then tucked about 1/4" under as I wrapped around the bucket to form the collar. Very carefully & quickly, I moved it to the top of the cake. Moving quickly, I Ickes that same 1/4" as I moved the rest of the fondant in place. I then used an exactly knife to cut the lapel.
Now the first time I do that, I didn't quite cut the second lapel side the same size & shape. On my second attempt, I used the first cut out to mark the second. That way they were exactly the same.