Ameritown kits

If you are talking about the clear plastic sheets, I used double sided Scotch tape, clear and very thin. Just cut them large enough so the tape does not show. I have 3 buildings like this and have had no problems.

Yes, that's how I did it, wall then tape. They are also removable that way, should you decide to change anything or put something else in the windows. As I recall I had to get pretty good coverage with the tape to keep things flat.

I cut the plastic to fit over each window and use cut pieces of Gorilla tape to hold them in place. 

Here is a "How Too Video" from my channel.

Good evening Trainroomgary, thank you very much for the video.

I never thought about using a cotton ball to dap the paint from the brick.

I have a MTH engine house that I want to whiten the mortar joints and keep putting the project off due to I don't feel comfortable with the project.

After watching this my next trip to the store I will be getting a package of cottonballs and will give this process a shot.

Thanks again for you knowledge and time.

Clear silicone also works great - moveable for positioning and it won't fog the plastic like glue will.  Also, I use clear plastic sheets from Hobby Town that are available in different thicknesses.  

Again, I much prefer the tape to any adhesive: I've found that a 3/8 inch wide strip of Gorilla tape overlapped half on and half off the "window" and pressed firmly will hold the window firmly and never let go.  It is removable if you wish to change the windows, etc., later on.

On many buildings, I cut off the slightly projecting small locator tabs on the back of the panels so they are completely flush and just tape one piece of plastic that covers the entire panel: easier and faster.

Note that you can turn the panel over once the windows are installed and paint or glue on curtains and drapes, etc., or place masking tape, etc. on the inside to simulate window treatments: even paint a vase of flowers near the window, etc.  I have done that on the buildings I show below.  Once that paint for the "curtains" have dried, you can paint on flat black if you wish to darken the interiors.  However, I tape a sheet of #800 wet-dry sandpaper over it (carefully, so it does not scratch the plastic).  Its shade and flat texture look much more realistic to me from the other side). 

Note the finally photo detail below.  There, I used transparent film made for overhead transparencies (you can still buy it) as the windows.  

The second photo shows a zoom view of two windows in the rightmost building in the first photo, made from bashed Ameri-towne panels (note it is four windows wide) it is a model of 221B Baker Street as depicted in the British Sherlock Holmes series starring Jeremy Brett.   I used MS Powerpoint and a bit of work to print, backwards, on what would be the inside, the 221B and "Commission for Oaths" on the rightmost lower window, as on the TV show.  More generally I have done lots of store windows, etc. that way on other buildings: storefronts, etc.