I have never used GG4;
but if you are using the good old fairy liquid, make sure you have not put too much of the stuff in your water, if your fingers feel slimy after you have put your hand in the bucket then you are using too much.
make sure your squeegee rubber is in good nick, when the edges start to round off they become less effective.
Make sure your applicator sleeve is cleaned out well.
And as Nick said, only wet a pane or two at a time, and make sure you squeegee each pane of cleanly without having to try and go back and pick up a 'kick' or missed bit.
Fairy is fine, you shouldn't have any probs really.
Or of course you can always try out the GG4 and see how you get on with that.
Good luck!
Ian