A site survey first, then access points placed and configured for your floor plan, your device count, and the interference that's actually present.
Coverage problems are usually placement problems, not equipment problems. A survey shows where the dead spots and the interference are, so the access points go where they are needed rather than where there happened to be a network jack.
01
Wireless site survey and heat mapping
02
Access point placement and installation
03
Separate guest and staff networks
04
Roaming configuration for phones and tablets
05
Post-install validation