The front view is almost straight but when I turn the cup the label gets distorted vertically. Is this because of the mesh being curved? Also I accidentally unwrapped the inside faces of the cup, how do you undo this? I'm new lol
first download this addon https://github.com/Radivarig/UvSquares to install it open blender and go to file, preferences, addons, install from file and seek and select the zip file that you downloaded and then click open-accept and then check the the lithe box that will appear when it loads and then save user preferences, then see how to use it with this pictures... and dont forget to scale it to fit it well in the whole uv map area.