I'm a long time After Effects user, but one thing I've never learned is how to properly create symmetrical shapes. I eyeball it painstakingly, enough to hide the inconsistencies, but I want to know how to make mathematically symmetrical shapes, especially ones that use bezier curves. Again I can eyeball it, but is the curve actually symmetrical?
For example, how to make a heart icon, or a tree icon.
The best way to do such stuff is to use Illustrator and then simply import the artwork or copy & pasting it over. Other than that you can employ the old trick of scaling e.g. masks by -100 %. Some of that may require temporarily pasting shapes on to comp-sized solids and/ or parenting layers to get correct coordinates.