Decreasing IP address lease time on the DHCP server can also help. I've run into poorly configured DHCP servers few times: they leased IPs for 24 hrs to WiFi users, rendering a 255.255.255.0 network practically too small because IPs were not yet available in the afternoon after users had actually left in the morning. Decreasing lease time to 10 minutes helped greatly. Of course, you need to configure this to your needs.

Just one thing to consider.