Get a Test Light!!

This tool you can get it cheap at Harbor Freight. It's a tool to test if you are getting power.

Let's say your passenger side power window is not working. And all the other windows are working.
First you would have to disconnect the up/down window control switch on the door. Get your test light and connect the side with the alligator clip and clip it to the body of the car. Make sure it touches bare metal, not to the paint of the car. You are grounding it.

Then hold the female connector that was connected to the switch and have the pointed end of the test light and stick it in the connector holes. Remember to have the ignition in the "ON" position. If the test light lights up in any of the holes, you have power, 99% the window motor is bad. The 1% might be a bad ground. In my experience I have not come across that yet.

You can also find out if your fuses are good or burnt. Just don't pull off the fuses from the junction box. Have the ignition on the "ON" position. Ground the test light and start prodding the back of the fuses. You can see the metals on the back of the fuse. There are two. Try prodding each one, one side will light up and the other should too. If one side lights and the other doesn't the fuse is bad. This means the circuit has been cut from getting power. Pull out the fuse and look at it to confirm it is a bad fuse.

This tool is very useful for me. I think I use it every day. Spend less than $5 for this tool or you can have a tech diagnose your problem for a $100. You do the math.