there is no method we all have our own way of pricing from what i have seen.
if you have just started your work rate will be slow, it will speed up as you become more experienced.
when i first started 15 years ago a £3 house would take me an hour, now the same house is £7 and do 4 in an hour. my hourly rate varies between £10 to £35. i have a minimum price of £5.00. dont over price you will lose work very quickly. good luck