In reply to Handles, Béziers & Points :
The positioning of the anchor points is the most significant thing to achieve a desired curve. If your anchor points are in the wrong position, you may spend hours (yes) trying in vain to get the control points "right".
To understand how to place your anchor points you must understand at least some basic principles of chirography and stroke modulation. Almost all control points come in pairs: for every point there is an opposite point (cf. the brace in your image) at the parallel curve. If you draw a line across each pair of points, you will find out their angle follows a nearly ductal logic. With designs that go apart from chirography the game becomes harder, but to be good at that you first need to fail, again and again, and I can't help you with that.
The principle is the same for the control points: Always think in terms of two lines interacting with each other :-)
I have always seen the "put your points in extrema" convention as a restraint.
