The article that Phil linked to is called Bookkeeping for Beginners.
It's a useful article but I'd like to add a few points and make a few suggestions to it.
Firstly - not all businesses need to keep ledgers, certainly not a purchase ledger. A one-man or one-woman business, selling its owner's own service, will almost certainly not need a purchase ledger. Put it this way, neither my video-making company nor my accountancy practice has a purchase ledger. No need to make your bookkeeping more of a chore than it already is :-)
Secondly - under the heading "Electronic bookkeeping systems" is the following:
Basic accounting software is more affordable than ever (budget £100-£180 inc VAT) and many deals come with free support. You could even set up a few simple pages in popular spreadsheet software, such as Microsoft Excel.
Dedicated accounting packages are easy to use – even for those with limited know-how. Errors can be corrected quickly (which is more complicated when using manual systems), you get a snapshot of your cashflow at the click of a mouse (this is possible, although slower with a manual systems), as well as find out about money you owe and are owed. Handy financial reports can be gained at the touch of a button. You can also view sales patterns and costs, which can help with forecasting and budgeting.
Well, to me, there's a big hole in the donut there.
Why not recommend a few packages that small business owners can use?
Keeping your books on a spreadsheet can sometimes be a good idea, but why go to all the bother of setting up even "a few simple pages on Microsoft Excel" when there are purpose-built solutions that would do it for you?
I'll fill the hole with some recommendations for small business bookkeeping/accounting packages :-)
After the simplest and most user-friendly solution around for small service-based business that isn't planning to grow? Try FreeAgent.
Looking for a system that's suitable for most small businesses and has lots of features to turn on and off? Try KashFlow.
Starting small but planning to grow? Want something that not only does your books but helps you manage your contacts, customer relations, stock, website and lots of other things too? Have a look at Pearl.
Strawberry jam donut.
And while you're at it, donut folks, please don't make people register in order to post comments - that's just plain annoying :-)