Stir frying is an art form and often people over cook the meat, under cook the vegetables and add oil rather than water if the food sticks to the wok. Stir frying as its name suggests is stirring and frying and that is what you need to continually to do with this method of cooking. It is so quick that all the ingredients need to be prepared before you even start to cook. If you take the time to do that, you will have a perfect stir fry every time. - Sal
It is worth spending the money on pure basmati rice as often there are less broken grains in the pack which means less starch in the water when you cook the rice so it is less likely to stick together.
Use ground nut or sunflower oil for stir frying as they are flavourless and they allow to cook at a higher temperature than say olive oil.
The egg should be in quite large pieces, so resist the temptation to stir it too soon.
The residual heat in the prawns and chicken continues to cook them and on returning to them to the wok they are perfectly cooked.