I recently had a window replaced in my house and still need a few more done. This is my story on a few issues you need to be prepared for when getting estimates and having a window installed.
Finding a quality company to replace my windows was the first step. I relied on two sources for finding installers to call. First, I spoke to my friends and neighbors. Then, I asked around for references from people I trust that had good experiences. Finally, I went to Google to search local companies and read reviews.
I found two local installers that seemed like good businesses and called both for an estimate.
This is when I found about all of the options. Wood vs.Vinyl, sliders or double hung? There are a lot of options these days.
Make sure to check local ordinances for any rules you must follow. My installer knew the neighborhood and informed us of fire codes that require certain size opening. This limited the options we had for window types.
During this process it may be helpful to ask someone, a friend or colleague, his or her opinion on your window decision. A second opinion is usually a good thing.
My last recommendation is to make sure to set appropriate expectations as far as install times. If you need it done quickly you need to let the installer know.