If you are not using microfibre then get some!
They are only a fiver each for the large ones, make sure they are of the 'flat weave' variety though, and get them from a window cleaning supplier and not from Wilkinsons or Macro, those are ok for sills and frames, but don't hold a candle to the proper ones for cleaning glass.
In hot sun, or rather on glass that is hot, don't have too much detergent in your water!
If the glass is hot, as it can be in direct sunlight, evaporation as you squeegee is much faster than on cold glass, too much detergent in the water will leave those smears you mention.
As tosh has mentioned, if you are using scrim and it is bone dry, open it out and give it a light 'mist' from your sprayer, that will help keep the lint at bay.
If you haven't got your squeegee technique right, and there are marks in the middle of the glass, don't bother faffing around trying to make good with scrim or microfibre, re-wet and re squeegee the pane.
You will only get problems if your technique isn't up to scratch.
And of course some of the modern glass has a more 'matt' finish that the old fashioned glass and this makes them horrible to clean.
I'm sure this would only show up properly under a microscope, the next time you are cleaning an old place with glass that is years old, check it out, if you haven't noticed the differrence....you will now!
Regards rubbers:
Soft is generally the best, you don't have to be quite so 'precise' with the angle between the rubber's 'edge' and the glass and you will be less likely to get 'kicks' on the turns.
However, each to his own, try out the different brands and the different rubbers they all do, after a bit of trial and error you will hit on one that suits you perfectly, and that might be a hard or a soft rubber.
Ian
