The Fiddly Bits
These are the bits of Salesforce I find drudgery and therefore avoid doing them, but they do make a difference to the end user. Every SF Admin needs to know about these and set them up in a clear and consistent way.
Views
See Views
Consistency of the fields in the views
Then adding new fields to specific views as they are needed
Views for each Record Type at least
View permissions - setting up public groups and giving access only to specific groups.
View Layouts
Search views
Page Layouts
See Rules for Page Layouts and Page Layouts
Complete consistency in page layouts
Mini Page Layouts for each page layout
And keeping them consistent
But with specific fields where necessary
Try to keep them the same as views
Consistency in Naming (especially for different profiles or different pages).
Related Lists
Consistent related lists
Sorting
Correct fields
Compact Layouts
If using Salesforce Mobile App
And keeping them consistent
But with specific fields where necessary
Try to keep them the same as views and mini layouts
Search Layouts
See Search
Adding them to all objects that need it.
Objects
Fields
Consistency in naming - eg
no Underscores
Shortened names eg Num