12. Upgrade to 802.11ac
The current Wi-Fi standard is still 802.11n, but you may want to consider upgrading to 802.11ac. While it lacks formal IEEE approval, 802.11ac is stable and works with existing gear. The new protocol can receive data at up to 1.3Gbps of data flow, about three times that of 802.11n.
I chose Netgear's AC600 WiFi USB Mini Adapter ($50) because it sticks out only an inch from the notebook. It improved my Wi-Fi reception from 3 bars to 5 bars on the Windows Wi-Fi signal strength meter in my laptop's task tray and extended the system's range by 15 ft. More to the point, my online access speed rose from about 9Mbit/s to 12Mbit/s.