Make sure you wash your glass last - I made the mistake of washing my glass before washing which looked fine at the time, but the shampoo left a nice layer of residue on the windscreen and wipers which smeared when I next had a few drops of rain - survivable if you hit a big rainstorm as the rain washes the shampoo off after a second, but if there are just a few drops it's less than ideal. Use the glass cleaner last to get rid of the residue.
I've used Auto Glym Car Glass Polish once, which worked well but is most useful for if you have small scratches on the windscreen or very stuck on dirt which can't be removed easily... I more regularly use Auto Glym fast glass, which I think is superb (and cheaper). Takes a couple of minutes to do the whole car, I just spray on and wipe with a microfibre, each window in turn, then switch microfibres and give each window a bit of a buff - I found a microfibre applicator pad works well here.
Also, make sure you clean your wipers! Another mistake I made, having squeaky clean windows but dirty wipers which mess them up as soon as I move.
I've got to the stage where I carry Fast Glass, a microfibre cloth and an applicator pad around with me along with the obligatory bird dropping wipes and quick detailer with it's own microfibre, I detest driving with marks on the window for longer than necessary.
One other thing, Fast Glass is very useful for removing white wax/sealant marks from black trim and rubber seals.