The Art of CAD: Art

Manage

if a component is to be used in different assemblies, do not create external references.
in-context features and parts are best used for one-of-a-kind parts that will only be used in the assembly they are modeled. Don't use them in multiple assemblies.
note that each feature of importance is named
to replace a component with its modified version, make a copy (Save as Copy), make the modifications, then replace.
use folders to keep things manageable (Constraint Curves and Temporary Planes)
don't use Windows Explorer to copy files. It'll maintain the original refernces. Use SolidWorks Explorer Pack and Go instead.
you can rename a part in SolidWorks Explorer. The file cannot be open in SolidWorks
use SolidWorks Explorer (Tools>SolidWorks Explorer) to modify unopened parts, assemblies, drawings
you can use SolidWorks Explorer and Pack and Go to save a state of your assembly (add suffix "AsDesigned")
you can replace an assembly with another assembly
design library is a storage area for commonly used parts, features and assemblies
on Save As vs Save As Copy. Save As with replace has usually better assembly success.

set display options, like Image Quality, to affect the performance of an assembly
create a new assembly configuration, then bulk-select components
define Envelopes, zones that appear blue and transparent and check parts relationships to that zone
like a part envelopes show up in the feature manager. Unlike a part, they also show up in the configuration manager.
you can RMB the envelope to show and hide components based on that envelope (make sure you're not "editing" the envelope).

features can have different end conditions and sketch planes for different configurations. You could create "in context" and "stand-alone" versions of the same feature.
can use configurations for different sizes: short/long handle, AA/AAA battery, forged/machined