Practical designs/practices for home electronics
Some maintenance and service manuals have complete schematics (Nokia and Fluke service manuals for one). However, schematics cover only part of it, as with code, design requirements, device usage (AC? DC? Automotive? RF?) dictate component and design choices.

Component manufacturers often have reference designs with good explanations for many applications. See if you can find an application note that fits your design and learn from it.