thats how you do the pattern, which I used for the summer long-sleeve and the variation:

Put the top on the paper, mine was smoked so I stretched it a little

and fold the sleeves inside at the seams, and draw all around

redraw the lines with a set square and draw a line in the middle

use the middle line to even out the neckline

thats how the part looks for now

next draw the sleeve on paper, stretched again

then draw the sleeve a longer (mine had to be over to elbow)

finished sleeve

I made the neckline a little lower

measure that the seams at top and sleeve are the same length

then add seam allowance and cut both parts

for me the front/back-part looked a little small, so I measure it and noticed it really was less then half of the chest-circumference

draw the part on paper again and add to each side, 1/4 of the cm still needed

measure the sleeve-seam again and make sure its the same length, if necessary also add some cm to the side-seams of the sleeves

my new parts, and then cut them