Am I ready - The biggest bit is actually having the confidence to do it and a CV good that will get you past both the gatekeeper (the agent) and the client checking CVs... That means you should have real experience across both multiple employers and multiple market sectors (retail, consultancy, banking for instance) before thinking about it.
Timing -
Never understood this one. Projects have different life cycles so require analysts before project managers before developers before testers.
Outside of the week between Christmas and New Year there are always some companies looking to start projects or requiring another contractor to fix a problem. In fact the only time I've found it difficult to get work is in April which supposedly is a boom period due to new financial years...
Bureaucracy -
The easiest way to find contracts is through agencies. To do that you need either a limited company or to use an umbrella. You don't however need to create this before you get a contract as you can get a company created in about 4 hours..
Getting an accountant
You need one but don't need 1 until you get that first contract. Crunch has a lovely interface and is a good site but frankly I don't think they would be that great if things went wrong as they haven't got many qualified accountants. Look at IPSE or Freeagent for many other possible options..
Registering for VAT
On the flat rate scheme you don't keep 5.5% but rather .2 *.145 or 2.6% as the 14.5 is taken from the income including VAT..
Expenses
You don't need to do anything until you have a contract (as I've continually said setting up a company can be done in 4 hours). You may need to wait before you get paid (although some agencies still pay weekly) but if that is the case you keep the expenses to a minimum, keep a record of them and take the money from the company as soon as it receives that money.
Finding your first client
The first client isn't the hardest. The second one is. Especially when your first client was a short term 3 month contract and they didn't renew you because the work was done. With 1 3 month contract under your belt you then start looking for a contract as your money starts running out. That is when things are difficult.
And I'm out of time but just before I go
Mailing lists and communities
This is my real problem with this article. He doesn't seem to want to be a contractor. He wants to be a freelancer working for multiple companies on various projects. Perfectly acceptable but thats the world of code bunnies doing work for start-ups and advertising agencies rather than contracting in a consultancy firm or government department.