9. Discounts
Some carriers offer discounts for seniors, teachers, military, or other professions. Your work place might offer a corporate discount. If you use your phone for a home business, look into deducting all or part of your plan as a business expense.
Your carrier might not mention these, so it is worth asking. Keep in mind that other carriers might just offer a discount, so it may worth changing carriers. And that plays into the next step.