If you don't have a day job or if you have become unemployed, substitute teaching is a great way to bring in extra income. You can select you grade level and what days or half days you want to work. So it is real flexible, especially when you have job interviews and job fairs to attend...
You need to have had good grades when you were in school and go through a background check. Most school districts have a telephone bank or a website where you can select opportunities ahead of time or block out days you can't, so that you won't be bugged by early morning phone calls looking last minute for an available sub (and you can avoid specific classes which you may have had difficulty before). See your local school board or school priniciple for more info. The thing is, once you accept an assignment, you must keep it or you will quickly be weeded out for future jobs.
I did this for about 1.5 years when I was unemployed suddenly. I found it helpful and rewarding. Also, one period of the day is for "teaching planning" which I was able to work on job applications and other things during that hour or block.