Start by updating your resume or CV which includes your gap period along with any additional skills, education or relevant experience you picked up along the way. Your cover letter offers another opportunity to frame your time away from paid labor as productive. Networking with your former colleagues is another important investment of your time. It will allow you to find out about current opportunities to jump back in as well as get you up to date with important changes in your field that you may need to be aware of in order to shine in your next interview. This will also give you a chance to check in with potential references to give them a heads up that they may be hearing from prospective employers.