They are hard work and I'm built for speed not power!
I use an extreme pole with a xtreme flocked brush and fan jets.
You need to apply a good chemical (I currently use screwfix no nonsense degreaser) I apply it from a backpack (do not pre wet) and apply lots of it. You need to let it dwell 10 mins. Give it a gentle scrub to agitate the dirt and then rinse and agitate. If you're lucky it will come off fairly easily.
Mix it up. For instance, do the front of the guttering, soffits, fascias etc. Then do the front windows with the custys tap. Then finish the windows with pure. This gives you a little break from JUST doing the soffits etc. I get all the front completely done, then the side, then the back. Break it up a bit and give your shoulders a rest. Also if the custy comes out, you can show them how the front looks completed (this usually goes down very well) and gets you a cuppa and biccies.