A good place to start is the File->Starter shapes and the "Quick Start" buttons (blue and green) on the File tab. As with Apophysis it is easy in XD to get fuzzy/noisy shapes (or even nothing but fuzz) and hard to get crispy shapes. XD seems a little trickier here of course, but is rather similar to Apo IMHO. Playing with the Starter shapes helps to give you a feel for it. There is another random button on the lower left of the Shape tab that will give you a random shape layout where the holons are all aligned nicely. Once you have an interesting shape you can play with the color tab (the randomize buttons are a good start) and finally the lighting tab. However to simplify you can always leave the color at white and apply color in the lighting stage. Very important: render at huge resolution (eg 3000x2000 or larger) and let the iterations get down below 300 - apply the lighting, save, and reduce it in PSP/Lview/PS and do your final PP. This is key in making nice solid/smooth looking shapes. Also, I found the standard Xenodream help file to be really useful.