Don't do it for nothing and make sure you make a living. Its far too easy to get caught in the trap of bring your price down.
Maybe I'm old school but I quote the price and they take it or leave it, but if they do take it they get the quality job they pay for.
Went to look at a rewire yesterday, a 3 bed in a bit of a state and needs a lot of TLC.
Potential customer told me he was waiting for a price off one spark and that he had already given another spark the work but he had called him before he was due to start to say he was getting out of the game and couldn't do it.
'Whats your budget I said' (always a good question to hit them with and save yourself some time) err about 'two grand' he said, although the spark I gave the work too said he could do it for