Measure the wall space, ceiling height, and desired shelf depth
Locate studs, outlets, vents, and baseboards
Decide on the bookshelf layout and number of shelves
Remove baseboards if needed
Build a base platform or toe-kick frame
Cut side panels, top, bottom, shelves, and face frames to size
Assemble the cabinet boxes with wood glue and screws
Install the units level and secure them to wall studs
Add center dividers or adjustable shelf supports if desired
Attach face frames, trim, and molding
Fill gaps with caulk and wood filler
Sand all surfaces smooth
Prime and paint or stain and finish
Reinstall baseboards and add final touch-ups