Recognizing the complexity of their Symbol object model and the value in being able to tinker with properties through a graphical interface, Esri developed their “Symbol Playground." Intended for developers, the app is divided into three sections: a map, a UI for selecting symbol options, and a code box. The basic idea is that you pick a symbol and use the UI to alter its properties (size, color, style, etc.). As you make your changes, a symbol with your selected properties will be drawn on top of the map and the code required to create the symbol will be displayed in the code box. When you’re satisfied with the symbol, you can copy the code and paste it into your script.
The app is fairly straightforward and I encourage you to try it out. Keep in mind that you can switch the map from 2D to 3D and change the basemap. This can be particularly useful since symbols often work much better on some basemaps than others. The only weakness I see in the app is that there’s no way to get back to the opening list of Symbol classes after you’ve already selected one. If you want to do that, you’ll need to reload the page.