Before You Start  -> Preheat the oven to 375°F/190°C/Gas 5 or whatever your particular recipe calls for.

First: How To Select The Best Baking Dish For A Successful Soufflé

• The type of dish most home cooks use is a porcelain or glass dish.
• But the best dish to use is a round metal mould which in France is known as a charlotte.
• French chefs sometimes use unlined copper bowls because the acidity of the copper acts as a stabilizer just as the cream of tartar will do. So for most of us who do not have an unlined copper bowl, we can use stainless steel, glass, or glazed pottery and add a pinch of cream of tartar to our egg whites. Don't stress over it as I can attest to the fact that porcelain or glass works well! But, an enameled cast iron baking dish is my favorite.
• Butter the dish well you chose to bake your soufflé in, then sprinkle with a little flour and turn it so the flour coats the sides and bottom thoroughly. Shake out any excess.

Secondly: How To Properly Beat The Eggs

• Always let your eggs warm up to room temperature. I place them in a bowl of warm water for about 20 minutes to warm up. (Don't get confused with whipping cream as it needs to be very cold to whip up to stiff peaks, eggs are different.)
• The importance of beating the egg whites is the main secret. The air when beaten into the whites forms the little bubbles, which help the soufflé rise when it is being cooked and form the beautiful golden puff.
• They should be free from any granules and so firm that they can stand up in peaks when lifted up with the beater - whether you use a hand beater or an electric one.
• Be careful! The egg whites will not become stiff if they have even the slightest bit of egg yolk in them! So when you crack open your eggs do not let a tiny bit of egg yolk escape into the whites. Crack them with a firm tap on a flat counter or table, not on the edge, which, as you practice will result in a crack line and not bits of crushed shell.
• The other point to remember is that your bowl must be absolutely grease free with not a trace of any fat/grease. So ensure that your bowl is squeaky clean.
• The other problem cooks run into is that once we have reached the point of a good stiffness of the egg whites we need to keep it at that stiffness. How do we do that? Well, we need a little acid in the form of cream of tartar - just a pinch per egg white, and this will do the trick.
• When beating your egg whites you can of course use the big whisk on your food mixer. Or a large balloon whisk which I love for mixing many things in the kitchen and find them so useful for all sorts of cooking jobs. But too tiring for me to whip eggs or cream for that matter, so I opt for the electric mixer. A small balloon whisk is great for making the sauce and for making custards, etc.
• When the sauce is made, you fold (don't stir) a large spoonful of the stiffly beaten egg whites into the warm sauce, then add in the rest of the egg whites folding until well blended.

Thirdly, How To Make The Base, Smooth Soufflé Sauce

• To make the sauce base start by heating the milk in a pan, up to the point of boiling but do not let it boil. If you are making a sweet soufflé you can add the sugar to the hot milk as it is heating and stir well to dissolve the sugar.
• While the milk is heating choose a large pan to melt the butter in, that will hold the sauce and the egg whites when beaten.
• Add the butter to the large pan and melt it gently, do not let it bubble up or brown.
• Add the flour gradually stirring constantly with a wooden spoon or, my favorite, a small whisk, until the two ingredients are well blended and smooth.
• Slowly add the hot milk, stirring constantly to avoid lumps forming.
• Continue heating and stirring until the sauce mixture has thickened. It will be quite thick. It is fine to add the eggs to the hot sauce doing it slowly.

Last Step to Soufflé Perfection

• Adjust one of your oven racks to sit in the middle of the oven between top and bottom.
• Preheat the oven to 375°F/190°C/Gas 5. (Hopefully, you have looked over these instructions before beginning and started your oven heating before anything else. A thoroughly heated oven is very important to soufflé success and cakes, as well as many other baked goods require a well-heated oven with no fluctuation in temperature.) This Oven Temperature Conversion Chart is handy to refer to for correct oven temps.
• When your soufflé is ready for baking place it on the middle oven rack (which you have already adjusted, as you do not want to lose heat moving it now.
• Start your timer for about 30 minutes, but that time may vary depending on how hot your oven is and the type of baking dish chosen.
• This will allow you time to get everything else prepared so you can serve the meal as soon as the soufflé is taken out of the oven.
• The soufflé should have risen about an inch above the bowl. DO NOT OPEN THE OVEN DOOR BEFORE 30 MINUTES HAVE PASSED, or it will deflate.
• To test if it is cooked, plunge a thin clean knife into the side of your soufflé and if cooked it should come out clean.
• Serve immediately as the soufflé will begin to reduce in size as soon as it sits in the cooler air of the room.