Give yourself time to grieve. Being fired is (usually) a crash. Take a day or two to absorb the shock before returning to the task at hand.
Calculate your finances. Knowing how long you can go without a job before finishing on the steps of financial straits. Use this timeline to help determine how it can be demanding in choosing the best job for your next adventure.
Apply for a job. Do not let yourself be in bed till late in the morning. Feeling purpose is the best way to cope with being fired. Treat your application process as work. Waking up early, shower, dress, have a cup of coffee, then click the computer to update your resume and apply to jobs.
Try to know company policies from those in HR careers. Most companies only disclose the time spent and the charge. If you are left on bad terms with a supervisor, contact HR and ask for the policies. It will save you headaches in the future. Be honest in your applications. Because your supervisor still works with your previous employer and he can only hurt your chances of getting a new job when he falls through your reference check at the new place.
Use your relationships with the network and find job opportunities. Let people know you are looking for a new job.
Stay positive and keep busy. Try volunteering for this unexpected downtime. It will leave the house, give you a couple of hours break from the job search, make you feel useful and could provide the opportunity to try a new career. You can find volunteer work that can lead to employment.