I will mention my standard mantra:
"Right tip right to GO right."
It's important to understand that these words describe a great mental cue to get things started on the right foot, so to speak. They are certainly not meant to describe the actual movements or technique in any kind of detail.
Why does the simple mantra work so well? First, it entails the mental pre-requisite to any great turn, as T-Square suggests--the offensive intent to GO down the hill (which is very different from the defensive intent to slow down, or to "stop going this way"). The "GO!" thought alone tends to stimulate all the right movements in the right direction, even before the turn actually starts. Since the exact "right" movements for any turn depend on exactly what direction you want or need to go, this GO! thought is an essential first thought in shaping your next movements. Intent dictates technique!
Second, while it focuses more obviously on the directional movement of guiding the new inside (downhill) tip into the turn, it does entail HelluvaSkier's thought to "tip" as the first movement. You cannot turn the right tip right until you have released its edge! So "tip" (or "flatten") goes without saying. How actively or passively you guide that downhill ski ("right tip right") depends on how quickly you want to change direction, and how tight a radius turn you intend to make.
And, while it focuses on movements that begin in the feet and legs, these movements can only happen if your body (center of mass) is in the right place and moving the right direction already (in other words, you're balanced). If that is not the case, you've got to fix that problem first. Active weight transfer (extending the uphill leg, or relaxing/retracting the downhill leg) with an open stance will redirect your CM, if needed. But if you finished your last turn accurately, your CM will already be moving in the right direction relative to your feet, and such unnecessary redirecting moves will actually detract from the smoothness of your transition.
Which brings up my final point. Because the movements of great skiing, particularly in linked turns, are cyclical and continuous, whenever you start thinking about what move to make "now," or "next," at any part of a turn, it is already too late! In great turns, everything that you have to "do" to start a turn is actually a continuation of movements that began much earlier. The "tipping" to release the edge that HelluvaSkier mentioned as the "first" thing, for example, is simply an extension of the "untipping" that began way back in the previous turn. Many skiers and instructors obsess over the initiation of turns, but beware. Many problems in skiing can be traced back to just this obsession!
In any case, "right tip right to go right" is as simple and effective a thought as there is to starting half your turns, anyway. "Left tip left to go left" will do for the rest! Give it a try if you can pry yourself out of that hot tub!
(PS--just noticed that you said you're thinking about what move you'd make "in powder." If you mean powder snow literally, the same things apply, except that you really don't want to try anything that involves extending or retracting only one leg at a time.)