Basically im with the above posters, a lot of how you pay your self is all down to your areas taxation measures once you start turning a profit.
Over here personal pay - tax is pretty simple for the self employed, first 11k or so tax free, after that its 20% till 30 something k then goes up after that. Weather you take it a bit every week or as a one off a year makes no difference here. Generally i kinda pay my self either what i need, or simple sweep excess profit out as my pay. the notion of x amount a hour is a lovely one, but that is not reality. Never been hungry or thirsty and have a roof over my head so its worked well for me so far.
Here if your a limited company your both a employee and director, thats were it gets complex, as a employee you have to have a wage and that has to conform to legal minimums + collect - pay tax and national insurance as per the differing levels. Though the company will in-effect collect and pay those from your pay before you get it. As a director of said company you can then pull dividends and other funds out far more tax efficiently than taking it all as pay, this is were you need the accountant and you need to follow a pretty complex bunch of rules but done right you come out ahead over self employed once you turn over enough.
Get either of the above wrong though and its you not the accountants that have to pay up!!! Hence it pays to ensure the advice you get is accurate.
Real key thing to understand though and keep a good eye on is the companies books, you need to understand your real costs and you need every job to turn a profit. Yeah some you win more than others on, but it takes very few bad ones to nullify a whole bunch of good paying jobs. Its a bit like bailing out a boat with a hole in it, key thing is keeping up and doing all you can too keep that hole as small as possible.
Hours are the meaningless bit, the bit the customer wants reduced, hell the bit you want reduced but can never figure out how.
Other thing is even when times are good, you need to leave some slush fund for a rainier day, few things are worse than turning down opportunities because you don't have the funds to make em happen!