hi mate.i started just cleaning the tops wfp first few weeks.with the occasional ground floor windows(good condition pvc).
basically your whole round will be a first clean nightmare!!

i started by scrubbing and rinsing all frames thoroughly all around the house.then back to the first window and just concentrated on the glass.scrubbing,scrubbing,rinsing,rinsing!
be careful of runs down the middle of 2 top openers ruining the pane of glass beneath!this was a common mistake i made the few weeks.
also be careful of water getting trapped under the top rubber seal on certain windows.as these can create runs and spotting.try and rinse just under the rubber seal(half an inch from the top) so it doesnt splash it.this also prevents water splashing up onto the top frame which could cause runs and spotting.
itll take time stick at it pal it will get better!much better!
after 10 months at it im really starting to speed up more and be quite relaxed about it.the windows will just get better and better the more you use the pole on them!
hope this helps!
best wishes
dazmond