This means a couple of things: First, you don't have to be perfect, something you would have tried (and failed) to achieve in the old days. Second, you can look at your first printing as a starting point instead of an end point. You can get your book out there, knowing that doing so is precisely what helps you make it better down the road.
I don't think you should go crazy with the concept and change your book every week, but I do suggest you make simple changes to your book every year. Here are some small (though not necessary minor) changes to make once a year for a simple update.
- Publisher's info: If your address, phone number, or website have changed, make it current. This is the single most important update.
- Typos: Your readers probably found a boo-boo or two after printing. Even the best proofreaders miss about 50% of the errors in a book. A standard practice is to have two proofreaders go over a book at two proof stages. This should catch about 95% of the errors. In your second printing, assuming you don't make many additions, your fixes will bring you even closer to perfect.
- Website addresses: Websites are terrific resources, and authors like to list them in books. Unfortunately, they are quite fluid. Check them all if you're doing an update. Ditto for any physical addresses on your resource page or elsewhere.
- Cover copy: If your book has been out for a year, you might have acquired some new testimonials to add or use as replacements on the back of the book. You may also wish to update your biography or photo. If you've acquired a blockbuster testimonial from a big name, you might even want to excerpt it and put it on the front cover.
- Coulda said it better: You may have identified sentences or paragraphs that you'd like to change. Here's where you need to be careful. The more changes you make, the more new errors you add. Also, the more changes you make, the more work you create for your designer and the greater expense for yourself. My advice is to be conservative with these changes--unless you've decided to pop for a "new edition," a marketing phrase that promises many changes and a new reason to buy the book. Think in terms of doing a simple update every year and, if your project warrants it, a new edition every two or three years. Where the simple update might cost $200 in fees from your designer and printer, the new addition might cost three or more times that.