Every school and district has a different system for scheduling substitutes. Some schools even require teachers to call and arrange for their own substitutes through a centralized district substitute bank. Make sure to learn the steps you must go through when you first begin teaching. It may be too late when you wake up early in the morning and discover that you're sick and need a substitute teacher.
If possible, do not wait to schedule your substitutes. As soon as you know you are going to be gone, make arrangements with your school. For example, if you have planned a field trip three months in advance, it is not too early to schedule a substitute for the students who will be left behind. There is a limit to the number of substitutes available. If the school district runs out of substitutes for a particular day, the teachers who got their requests in early will receive preferential treatment.
Ask veteran teachers about any advice they have concerning absences and arranging substitutes. Sometimes they will have insights that will allow you to better understand the system for scheduling substitutes and may be able to give you time-saving tips.
Temporary duty situations where you are doing something for the school are quite different from personal days you might take. Most districts have policies regarding appropriate uses of sick and personal days.
Usually, this means that teachers cannot use these days for vacations. Instead, they are meant for situations when you truly are sick or when you have a doctor's appointment scheduled. Make sure you check your school district's policy concerning using these days before making plans.
Despite all your efforts, there will be times when you will need to call in at the last minute to get a substitute. Most schools and districts have a cut-off time by which you need to call. Hopefully, you will have a nice person who is in charge of answering the phones in the morning and who remembers that you are calling in because you are sick.
Many districts do not allow you to call in sick the day before or the day after a holiday. This stops teachers who would abuse the privilege by taking an extra day of vacation. However, if you are truly sick, you should still request the day off.
However, if the person is not particularly nice or caring, do not allow yourself to feel guilty for doing what is in your best interest. Remember, she is probably stressed too. You should make sure to stay polite and keep things on a professional level at all times. Remember, this person may be a huge help to you at some future point in your teaching career.
Again, it is a good idea to have lesson plans prepared just in case you are going to be out. This is especially prudent if you are beginning to feel ill when you leave school at the end of a workday. If there is a chance you might take the next day off, go ahead and leave your lesson plans and substitute folder on your desk just in case. It is also a good idea to make sure the teachers around you and the substitute coordinator know where your substitute folder and emergency lesson plans are located.