What are your needs for speed and range? If you play games online, trade files heavily or your network consists of distantly separated rooms, wireless-N will work better than wireless-G. Wireless-N may help reduce interference, as well.
What is the difference between theoretical speeds and real-life speeds? While the most advanced N-routers promise speeds up to 450 Mbps, in real life, you'll see speeds much lower, around 200 to 300 Mbps. That's due to many factors, including interference, Internet provider and your network equipment.
How old is your equipment? A wireless-N router cannot make your older equipment run faster. In fact, Tim Higgins of SmallNetBuilder.com cautions that a wireless-N unit "could end up causing problems with very old gear."
How many computers will be in your network? Understand that you need network adapters for each computer you add to the network. Your desktop or laptop probably already has installed wireless networking components, but you might have to purchase an internal or external network card; consult your computer manual. Reviewers suggest buying a wireless router and adapters made by the same company if you can. This facilitates both setup and technical support, and it is sometimes necessary for compatibility.
Will other household electronics cause interference? Expect that cell phones, microwave ovens, cordless phones and other household electronics may cause annoying interference with a wireless network. If you have a cordless phone that uses the 2.4 GHz bandwidth, you can avoid interference by upgrading to a 5.8 GHz or 1.9 GHz DECT phone. Wireless-N routers can operate on either the 2.4 GHz or 5 GHz bands; newer dual-band, dual-radio routers can work on both at once.
The latest premium wireless routers are in the N900 series, with simultaneous dual band speeds of potentially up to 450 Mbps per band. Look for wireless routers to have two or more USB 2.0 ports, rather than the usual one port, and for models to incorporate a USB 3.0 port. Wireless-G technology will continue to fade, as most new routers are wireless-N.