TIP #1: Make sure to rinse the beans and tomatoes. You do not need the extra sodium or the extra sauce.
TIP #2: If the mixture is a little dry, add some of the pasta water.
TIP #3: Thaw the frozen spinach in the microwave prior to cooking it. Not only does it save you time, but it also prevents loosing heat in the pan, which is what would happen if the spinach was frozen cold when added.