Personally speaking from experience, unless you know what your doing, i wouldnt bother. Takes too long, messy and its a hard job and unless your price well youll be kicking yourself.
I priced a walkway once at front of bungalow round to back which i thought would take about a hour...took 5 hours and id only said £50.
Others might tell you other wise but i wouldnt bother. I had a good pressure washer and sold it few months ago as was doing my head in.
Window cleaning...pull up, clean window gone.
Pressure washing, pull up clean for ages, start getting ticked off with it. Tidy up the mess, get covered in crap etc etc