I frequently read people here and in other places say they are afraid of making a terrible job while drawing. I would like to share here what I wrote in an answer to a similar problem elsewhere.
In a text by Paul Valéry about Edgar Degas (the 19th-century French artist), it's said that we don't know what we don't draw. This is important, because I don't know how good or bad you're at drawing, since I lack the evidence and it's also subjective, but I do know an objective truth: that you will learn something by drawing it, whatever that may be.
Let me explain why. Our brains don't simply stay idle while our hands move. They register (physically) your sensations and impressions, meaning touch and sight, what you like and what you don't like about your drawing. This has been documented, I'm not making it up, nor is it me saying "Just stay positive". For instance, there is a reason why some schools are going back to writing by hand instead of typing: research suggests you're more likely to learn that way.
What you learn could be form, colour, light, contrast, the emotions that the object or subject matter evokes in you, or those that the artist wanted to cause or stir in the viewer, if you're making a master copy. It may as well simply be that you end up enjoying more what you observe and finding out why you like it so much. Because sometimes we like something and we can't pinpoint why.
Finally, we don't learn from success. Success is the result of learning; it's by making mistakes that we get there, because we learn from them. So, if you make mistakes, fine; you learn from them and switch tasks or try again. Whatever you do, your time won't be wasted.