So how to shoot through glass to get the best pic possible. First make sure the glass surface on your side is free of smudges, next set focus to infinity, set f stop to 3.5-5.6 range and most importantly, put the lens on the glass window, flash off. Compose and here is the trick to get the sharpest pic............. set the self timer control to two seconds, exhale, hold the hands steady and depress the shutter. With practice you will get a decent shot.
Of course, the ideal way is to have no glass and a tripod!
A little PP in PS and you have a usable image. Enjoy, Jeff