are you in a town or in the country?, fuel costs differ
before you start do a bit of research and find out what the firms that have employees are charging, near you. personally i pitched in a quid or 2 under them and work out a price structure thats easy to remember (such as "quid per window" or whatever) and stick to it .you are setting your stall out ,so start as you mean to go on
i have been trad only and only 2years in,(could have acheived it in under 1 year from scratch,but i wasnt fit enough and found it better to ease into ,rather than in at deep end) but now have a cracking full round . Being honest with you , its tough physically but very satisfying and the overheads are pretty much zilch , apart from some diesel and rubber for my squeegee . Getting used to ladderwork is like everything,hard for first 6 months but then o.k. after you get the hang of it .
dont hurry to dismiss trad out of hand , consider it ----- the overheads are pretty much zilch