ProductionCrate offers a quick overview of UV Mapping aimed at beginners.
Understanding UVs is one thing, and working with UVs within various workflows is quite another. If you are new to creating computer graphics and 3D, check out this overview for UV mapping offered by the folks at Production Crate.
“This essential technique for 3D modeling and texturing will help you get started.”
You can also check out this tutorial from MeshMen Studios Peter Aversten, who covers the complete process for creating UVs on an instrument gauge. The tutorial covers planar mapping and then shows how you can move and sew UVs. Also shown is how to unfold and maintain uniform texel density on the object.