Put the feelers out in the area you intend to clean in, see what the guys are already charging and what type of service they
are offering for the price.
Lets say most are charging a £10 for a certain type of property but are only cleaning the glass, then you could do the same
or offer a glass frame and sill clean for a higher price.
Make sure you take your price from the guys that have been going for a while as guys who work for peanuts don't seem to last
even better guys who employ as that's a good indication that they have set a good price.
Don't undercut because this very rarely wins work in this business.
Its up to you what method you choose to use traditional methods, ladders mops and squeegees or water fed pole, the first is
cheaper and the second is slightly more expensive to get started in but safer, either way there are plenty of videos
online that will show you how to do both.