using the pen tool to create fashion flats

in our computer studies class today we used adobe illustrator to create some fashion flats like this:

i found it quite challening as you need to use the right part of the tool in order to get a good, clean line. i kept on having the lines become curved so i found it difficult to keep the lines straight to have them crisp.

i think a way to make it easier is that i have to practise more so that i am more used to the own tool as we havent used it in a while.