Here's my mini tutorial on another technique to copy pictures.
How to use negative space and positive space to check your copy picture:
The area coloured in PINK is the area we're used to seeing and drawing. This is called "positive space",

The area coloured in BLUE is called NEGATIVE SPACE. In this case the negative space is the background, people sometimes forget that a like the positive space, it's important to draw the negative space correctly as well! When I draw I tend to check both positive and negative spaces, when you change between them it'll give you a fresh perspective on things that you thought were correct : >.

Now I'll show you a practical example of how this can be used. I think Cure-kun from DCW for volunteering his pictures for my tutorials \o/. Thank you so much <3!
Let's say the drawn version of Heiji's hair is bothering you, but when you look at the measurements and positive space you're not sure what's wrong.



Best of luck <3
-kirite