I listened to a podcast the other day and the author talked about how they--meaning, him and his indie publishing team--would regularly audit their back list.
A back list, for those who may not know, is the entire list of your publishing works. Everything you've written.
What do I mean by audit?
Audit is to review the product. Is the cover okay? How about the keywords, the synopsis/book description, and even links, etc. inside the book? Believe it or not, what you did years ago may not be relevant anymore. Links you had to a free book may not be the best fit anymore. And so on.
I've been doing this a bit, from time to time, but now I have a set schedule to look at a few things on a quarterly basis. This isn't going to require loads of time, but if I can improve a book or two by improving keywords and/or book description, or even the cover, or update links it will help down the road.
On a side note, I've been quite a busy beaver lately. After I set Shades Of Darkness up on pre-order--the book is out now!--I wrote a Halloween-themed novella called Grave Secrets. Then, I'm planning on a Christmas-themed novel. This one will be quite a different story than what I normally write, but it's been in my head for close to a year and I'm itching to get it done before the holiday season.