As most of you already have said, stealing art is wrong! 
Here are some thoughts on tracing and using references:
The case of tracing, or trying to copy an image/drawing you like, depends on the situation. For practicing and personal use only, go ahead. If you ever want to share the traced drawing donât claim it as yours and always give a reference. Also donât âgive awayâ the traced drawing since itâs not yours.
Depending on the situation and how you do it is key. Be respectful and humble. If the purpose is purely for practicing do whatever you like. When it comes to sharing be thoughtful, and you have no right to distribute. Unless to your mom, dad and friends. Use your judgement and ask if youâre unsure.
When it comes to royalty free stock photos I guess itâs okay to distribute it however you would like to. Just donât claim the concept as your own, and its always nice if you give credit and link to the source. 