If you're planning to re-enter the workforce after an extended break, and you have kids that aren't newborns, it might help to consider the change from their point of view. Most kids find comfort in routine, so at least starting to establish a new routine, before you actually start the job, is likely to make the transition easier on everyone.
Think ahead. Chances are that you will need your kids to do more for themselves if you're going back to work. Asking them to take on more responsibilities around the house is great for them, and it should help you too.
The key to a smooth transition is to be sure that your kids have taken on these new responsibilities before your first day on the job. Even relatively compliant kids will need "practice" before new routines run smoothly. We found that our kids usually threw three "fits" in a row when we imposed new routines on them. If we could endure those "fits" (which usually were just complaints, whines or worse), and stay firm (and consistent), the new routine tended to click by the fourth iteration and the kids often became enthusiasts. Maybe we're all that way :)
Here are ideas for things most kids can be expected to take on around the house. Obviously their ability to take on various responsibilities will vary widely based on their ages.
Most kids are happy to help when they know that their contributions are meaningful; it gives them a great sense of accomplishment and helps build lasting self-esteem. This means that while they're taking on a new responsibility you need to be sure you're not hovering over them, offering too many suggestions, and/or criticizing their efforts. Let them make a few mistakes! Keep yourself busy doing something else meaningful while they tackle their new "jobs".
An important key to success is to be sure that your kids don't view your return to work as an imposition on their routines or a punishment. By establishing new routines before your return, you're likely to ease the transition for everyone and discover how your work actually helps your kids become more capable adults in the future.