In general, insecticides will not affect spider mites, so your arsenal of pesticides should include an insecticide and a miticide. Horticultural oil can be an effective contact insecticide for both insects and mites, reducing populations to a level where predators can exert some control. If you purchased horticultural oil as part of your fungicide program, pick up extra for insect control. Read the label for application rates, since insect control may require more material. As with any insecticide, use horticultural oil at insecticide strength only when necessary to control a visible pest.
Pyrethrums can also be a useful contact insecticide for reducing insect pest populations.
These two products may be all you need to keep your pests under control. Thrips, however, can be especially troublesome, and spider mites can multiply rapidly out of control before you notice them. At this point you may need to turn to stronger measures. For spider mites, Kelthane is readily available at local hardware stores and nurseries that have a broad selection of pesticide products. In my greenhouse, I keep a pump spray bottle of pyrethrum for whiteflies.