As someone with nil background in finance getting to grips with GnuCash has taken some time.
I've got two databases -- one for my personal finances, and one for my grants. I'll only show how to set up a database for personal finances here.
For most of the steps there isn't much to say...
Choose the simplest type of account -- Checkbook.
Double-click on the Checking account, put the current amount of money in your account under Deposit, and select Equity:Opening Balance under Transfer.
You now have money to spend.
Time to customise the set-up. Create an new account -- select placeholder, income and New Top Level Account. We're calling it John Doe.
(You'll find that only top level accounts can be all types of accounts. Some accounts can only be income/expenses, while other types (e.g. Bank) can't be either of those.)
Note how it says Imbalance: 3,000 (the amount added to income/salary). Transfer that money (income/salary) to your checking account:
We can move money from the checking account to cash (i.e. ATM withdrawal), pay by cash etc.
Here's the double-entry aspect of GnuCash -- every transaction shows up twice:
Here's another overview of the accounts:
Anyway, at this point it's fairly easy to start exploring and setting up more complex accounts.
Essentially, GnuCash SEEMS to be powerful, but for some reason I can't bring myself to read the documentation. Maybe it's the way it's written, maybe it's the topic at hand (few scientists relish the dirty world of money...or so we like to think), or maybe it's just me. Regardless, it's a piece of software you SHOULD learn how to use if you need to keep track of spending -- as most scientists do.