There are several ways that you can improve your WiFi connection, the most efficient usually to pass by improve the device that has, with better place the router or just change a new one with better speeds.
However, the few things that can be done directly sitting in front of your computer and without having to remove the aluminum foil and the ladder, there is simply change the transmission channel for the most ideal.
When configured wireless router for the first time, it automatically selects a transmission channel signal. In theory, the device should be able to choose the best, but who do not is more common than it seems, especially because it can happen that when the router chose that channel a year ago, perhaps it was the best, but then the neighbors installed new equipment or began broadcasting on the same channel as your router, and this was saturated by slow your Internet connection.
How to choose the best transmission channel for your router:
All you need is an analysis tool that you can easily determine which is the best available channel in the space where it is located. In Android, Windows has the free app WiFi Analyzer. Mac OS has its own wireless diagnostic tool that you can find from Spotlight.
All you have to do is run the application and let it do its magic. Once you have the outcome, you must enter the configuration of your router (this varies among all brands, so use the instructions). Find the options related to your wireless network, usually in the same place where you choose network name and password, and change the channel to the recommended one into the analysis tool.
Oh, and if your connection is too slow for mysterious reasons that may not because of your service provider, check to see if someone is stealing your WiFi.