After you get your database of choice set up, Quasar is very easy to use. And this from a guy who wouldn't even begin to call himself a wizard of the accounts—at best, I might be able to scrounge up a hat. As you get going with the software, you'll want more than the basics I've covered here. There are excellent and detailed manuals (in PDF format) available free from the Quasar Accounting website.
As I mentioned in the introduction, Quasar is free software distributed under the GPL, and as such, using it in your business won't cost you more than the cost of the download and some setup time. You can sign up for the retail model and pay for support or buy the point-of-sale module if you need it. For most small businesses, however, Quasar Accounting's price (free) is simply too good to pass up.
Until the next walkabout, I bid you great Linux adventures!