Sometimes we don't have the freedom to set dimensions or to select stock. For me, at least, when designing something I have an overwhelmin tendency to deisgn a dimension to a nice number so I would pick a height of .5" I would then select stock of 1/2". Why would I buy stock with 5/8" just to throw away the excess 1/8"? A better approach would be to design the part with a thickness of .45" so I can leave matreail for fixturing. The same applies to length and width. If we leave additional material for clamping, it can make our lives much easier.
One of the most overlooked lessons in machining is optimizing order of operations. For accuracy's sake it is desirable to complete all machining operations with as few setups as possible. Leaving yourself a handle or set of handles to hold the work and parting them off as a final operation makes for easier and more accurate machining.
As an example, I had a part which required machining on five faces, using 20 tool changes The smallest feature was .008" so accuracy was important. The stock was welded to a stub mounted to an RT oriented vertically. The stock could now be rotated to expose four faces for machining with the fifth face needing a facing cut. The 70+ operations were all done with the same setup with the final operation being parting from the stub.
The work was done on a mill/drill with a freshly installed DRO and the part, which mated up with a similar part, was successful. All the optical, fluidic, and dowel pin features aligned perfectly.
