Starting off with the basics, I wouldn't use Microsoft Paint/Paint3D for making textures, the tools are very basic and are watered down compared to other professional programs out there, some of which are free to download. Personally I use either Paint.NET (which is free) or Photoshop. I find Paint.NET best for basic texture editing IMO.
The dragon sticker has a lot of rough edges and gives the impression that it was poorly cut out, or was just cut out using some kind of wand tool. What I use for cutting out images is the Lasso tool in Paint.NET, I carefully cut around the edges and delete the background from the image. For me it usually takes around the same time you took to make your sticker or less once you get used to it :)
Just leaving a constructive review to help you make better textures, nothing personal. Don't take any offense cause of it, but use it as a learning tool :D