We make Valentine’s cards for one another here. This year I went out on a quest for the perfect heart-shape. A good blend between proportion, curve, and size. The best I discovered was very simple. Take a square, and use two adjacent sides as the diameters of circles. The result, when rotated by 45 degrees, is a darn fine heart shape, though I say it myself.
And the best bit of all is it is really easy to program, when you want to create a card with ten thousand hearts on it, for example 🙂