If you're in an apartment that provides you Wifi as a part of your rent, and you can't bring in your own provider -- you're likely stuck with your speeds and service.

If you're in an apartment or home where you can pick your internet provider - then you'll only be limited by the service they can get to your home.

At minimum?  You'll need two things:  A modem and a router.  Sometimes providers combine both into one device, but in other times, (and better for you if you read on) if the devices are separate it gives you more options.  

The Modem:  Takes the incoming signal from your providers and translates and decodes it into a usable signal

The Router:  It distributes that decoded signal into your Wifi Network or directly to a device if you use a wire.

See below for a image on how this works  (The cloud on the edge is your "ISP" or Internet Service Provider)

Image Source:  HowToGeek.com

One thing to keep in mind, your internet service provider wants to keep costs as low as possible.  So the router they give you, may NOT be the best device in the world.  Sure, it works, but in many cases it's not optimized for more than a handful of devices.  The more devices you add, the more load you'll put on that provided router.

Sometimes spending a little extra money on a router CAN resolve speed and device issues in the house.  Most routers will come with capacities listed: such as "This router will support 5 to 10 devices" or even 20 to 25 devices!  Obviously the cost goes up the more features you add, but this IS a great option to consider if you can afford it.

If your router is more than 3 or 4 years old?  Time to replace it.   Routers get old, technology changes, so that is always a good device to update occassionally.

Where you place equipment can make all the difference.  If you bury it in the corner of the basement and you're trying to get a good signal to the second floor loft?  It's not going to work so well!  While signals CAN get through 2x4 wood and drywall, the more layers you force that Wifi signal to get through, the weaker the signal will get.

We recommend centrally locating the router if at all possible.  Sometimes you can have your provider give you a cable to help locate that router in a different spot (if for instance the modem is in the basement), ask if they can get a cable up the stairs or into a central room on the first floor.  They might charge you too - just make sure you ask first. 

We know some areas of our district do not have great internet service (because of rural locations or the provider doesn't have adequate infrastructure where you live).  So some people get a "hotspot" or Mifi unit from their cell provider.  

BUT BEWARE!  If your cell service is not reliable where your house is located, a Mifi will not solve your internet speed issues.  A Mifi is just a mini cell phone, just without any touchscreen or way to interact.  It literally just connects to the cellular service in the area and then distributes that signal as a Wifi Network in your house.  

Be sure to check your plan too!  If you are not on your own network with your own cell phone, and the Mifi hops on a off-network cell service?  You might see a HUGE bill the next time you have to pay for that!

Just like a computer needs a reboot, your ROUTER and sometimes your MODEM will need a restart!

Yes, just like doing a restart on your computer, laptop or device at least once a week, you can also do the same thing for your modem and router set-up.  You probably don't need to do this once a week -- but even once a month can help your service in your house.

We recommend putting those into a power strip, so you just need to flip the switch off, count to three, and then turn the power strip back on!  You should see better performance once it reboots.

A simple Google search will give you an option right away.

You can also use this speed test link:  www.speedtest.net

What speed number do you need?  A minimum of 25 Mbps download is necessary for a smooth experience for a few devices in a house.  As you add devices, you'll need to make sure that number keeps going up.    If you have 4 users in a house?  You'll probably need closer to 200 Mbps.

For more detail, you can use this site:  How Much Internet Speed Do I Need?