Heat the oil or fat in a wok. Groundnut or vegetable oil are fine, maybe with a dash of sesame oil for extra flavour. I sometimes also use pork fat saved from an earlier roast, bacon or other such.
I like to throw in some black mustard seeds when it I think it is ready, and they will pop and jump if the oil is hot enough.
Make sure everything is ready to hand for cooking, and the you have set the table and got the serving utensils ready, and warmed bowls or plates if you need them. You'll need 100% concentration on the frying for a few minutes!
If the dish includes meat, I would cook it twice. Stir frying is great for left-over meat from roasts or other meals. If the meat is fresh, I wouldn't just toss it in the stir fry with everything else. It is likely to give out too much liquid. I'd fry or poach it (in sake, soy sauce and mirin), and then put it aside, reduce the liquid and use that as the base for the potion. More on potions here.
Keep the heat high, and keep stirring! Throw in the meat first, and make sure it is starting to brown, then pour in a little (c. 0.5-1 tbsp) of the potion. Let the sauce evaporate before throwing in the veg. Don't put them all in at once - it will reduce the heat in the pan too much. Phase their introduction with the things that take the most cooking first (mange-tout, chilli, garlic, ginger, carrot), then medium items (mushroom, spring onion, pak choi, chinese leaf) then things that hardly require any cooking (bean sprouts, sweet pepper), although cooking times will depend on how you have chopped them. Add a little of the potion from time to time, but only as much as will evaporate quickly - don't flood it and start poaching the food instead of frying it. Straight after the last veg add the noodles and then the rests of the potion. Ensure it is all piping hot and then transfer everything to a warmed bowl. Serve and eat!