The rule of thumb is that people read the summary at the beginning and then look at the cashflow projections at the back.
So when i'm writing them, i start with the cashflow which makes you ask lots of questions of yourself about how much you think you're likely to earn, when in the year you're likely to earn it and it'll slowly come together.
Definitely financials first. Most people can waste hours/days on the narrative and then hit the financials and find it doesn't work financially or they simply can't work out the financials.
Do the financials first - that will highlight any weaknesses in the figures (either the figures themselves or your understanding of how the numbers work). Loads and loads of templates etc on the internet.
So: the story is, I started working as a consultant for this company a year ago after a dozen years working completely alone. The company is owned by one person, Bob.
The pay is poor but I quickly saw that there was loads that could be done to grow my own specialist area of work. Bob has an amazing network/client base but they don't send the work I specialise in to him (yet). Bob and I broadly agreed that I would write a business plan on how to achieve this growth. I hope Bob will agree either to give me shares or up the charge-out rates (leaving more margin to pay me more).