A typical home's Wi-Fi signal can be improved in just a few minutes with some basic tweaks. For more improvements, look to your hardware -- routers, repeaters, and extenders. And be sure no ancient Wi-Fi devices are dragging down your network.
Upgrade to 5 GHz Wi-Fi
Most wireless routers out there are still operating on the decade-old 2.4 GHz frequency, while modern 802.11ac routers operate both on 5 GHz and 2.4 GHz. New devices compatible with 5 GHz automatically connect to the 5 GHz Wi-Fi, while your older devices can connect to the 2.4 GHz Wi-Fi.
5 GHz is a less cluttered part of the spectrum. Most of your neighbors are likely still using 2.4 GHz Wi-Fi, so there's less interference on 5 GHz. More importantly, 2.4 GHz Wi-Fi only offers three non-overlapping channels -- channels 1, 6, and 11. Meanwhile, 5 GHz Wi-Fi offers 23 channels, and none of them overlap. Older 2.4 GHz wireless devices like cordless telephones and baby monitors won't interfere with 5 GHz Wi-Fi, either.
The bottom line: Assuming you have 5 GHz-compatible devices, upgrade to an 802.11ac 5 GHz wireless router for less interference. Devices that support 5 GHz will get a boost, and 2.4 GHz devices will continue to function like they did before.
Extend Your Coverage With a Repeater
Repeaters allow you to extend your Wi-Fi coverage. They are useful if you're trying to cover a large home -- or a home that has nooks and crannies where the signal doesn't reach. You can extend Wi-Fi to the farthest corners of your property with one or more repeaters.
Head to Amazon (or another store where networking equipment is sold) and search for wireless repeater or wireless range extender. Be sure to buy one compatible with your router -- so, if you're upgrading to an 802.11ac router, get a range extender that supports 802.11ac. It'll work even if it only supports an older standard, but it'll repeat traffic using that older, slower Wi-Fi standard.
These devices are fairly simple to use, and many of them are small enough that they can just be plugged into an electrical socket like a night light. They function as repeaters to extend the Wi-Fi signal, which means you'll just have one single Wi-Fi network you have to log into -- not multiple ones. Some routers can be configured to function as wireless repeaters, so you could potentially use an old router you have lying around instead of buying some new hardware.
Get a More Powerful Antenna
Rather than using a repeater, you might purchase a stronger antenna for your router instead. A more powerful antenna can boost the range of your router's Wi-Fi signal, extending Wi-Fi coverage and improving all around-signal strength.
Check your router before buying an antenna. You'll need an antenna that's compatible with the connector on your router. Buying a pre-made antenna isn't the only way to go, though. There are all sorts of DIY antennas you could make out of everything from an old aluminum can to some tin foil.
Decommission Wireless B Devices
If you have any devices still using 802.11b Wi-Fi, they're slowing down everything. Wireless B was the first successful Wi-Fi standard, and it debuted in early 2000. It was replaced by 802.11g in 2003.
Modern routers are still compatible with these old 802.11b devices, but they have to function in a sort of compatibility mode when 802.11b devices are connected. This slows down the Wi-Fi connection for every device on your network a bit. If you have any old devices still using 802.11b, it's time to replace them. Modern Wi-Fi standards don't have this problem -- you can connect an 802.11g device to an 802.11n network and it'll function at wireless G speeds, but not slow down those wireless N devices. Check your oldest Wi-Fi-enabled devices and ensure they support 802.11g at a minimum.