I do what a lot of guys on here do, and estimate how long it's going to take me and what I want to earn as an hourly rate (taking into the fact that you can't work every day because of weather, sickness, holidays, bank holidays, van breakdowns/MOT, equipment failures etc etc.). Basically 20 min job is around £12. Poor access, call the night before, less regular than 4 or 8 weekly, position on a road (i.e. whether it gets filthy or just normally dirty), whether (in my patch) it's a farm (always very dirty, hose trailing through cow poop, grit inside pole that needs washing out etc) all adds to this basic figure.
My advice would be: hide the tats and grow your hair if you are a skinhead - look smart and conventional; ditch jeans and a T shirt and get a 'uniform' (mine's black Dickies trousees and a white polo sirt; a black gilet; a black fleece). Say hello to everyone you see on the street, be reliable, do the best job you can every time, do the occassional easy freebie when you have time and the weather is with you - but always point it out to the custie, knock or ring on bungalows in case they are indisposed. Basically, fit in and be professional.
When pricing explain there's no limescale in the water you use if you are wfp and show them the indsides of your van - digital flow controllers are great as they look hi-tech. Explain you clean the frames every time. Explain you are insured and you pay tax where others doing it for tuppence may well be signing on or have second jobs or be retired and doing it to top up the pension.
There are a lot of lads running around doing a lot of windows and not earning a great deal. You can be busy but you want to be profitable. If you have fewer well priced jobs it leaves you with the same income and time to take on more of the same. The reverse is also true.
These are just my opinions.
Cheers
Stick to your guns