For this you can help with some pins, but as I like fast things and what I want most is to see the final result of my cropped jeans, I just fold it and go to the next step.
Well, it was not exactly a pencil, pencils are missing in my house but the pink colors of Carlota and Fedora abound. With whatever you mark, try to make it clear and make the mark long enough so that you can find it if the jean you are going to cut is very dark
You are closer to having your cropped jeans, you can already remove the cowboy !. On a table (or something stiff) put the pants, turn the part you want to cut and highlights one of the legs of the pants (it is not necessary to do both) with your fingers or fingernails enough for the fabric is marked. You can also do this step with an iron, but I do not know if you know, but the iron and I are not very friendly.
With the help of a rule, and following the mark you made in the previous step, make a straight line. This line will serve as a guide to cut it, so try to be as straight as possible.