Here are some basic tips for stir-frying:
--Use a high-heat resistant oil like peanut oil for stir-frying.
--Think about the sizes of the meat and vegetables so that you add them in the logical order for even cooking. For example, add carrots before zucchini or red peppers and asparagus before corn kernels.
--Make sure the wok is very hot and almost smoking to achieve the desired effect of browning to seal in the juices.
--If you still need to finish cooking the stir-fried dish, add a bit of broth, cover the wok and reduce the heat.