Could you elaborate on your use of the bestiary method? Is it like the one discussed in this thread?
As for constellations, perhaps you could try to envision the animal/object they represent (in the same pose of course), then use that as a memory palace to encode further information. Sort of like is shown in this illustration of Leo:
So you’d see the Lion (presumably in your memory palace if you want to remember the sequence of the constellations as well). You’d then ‘zoom in’ on his paw to find that a crown is wrapped around it (from latin ‘regnum’), which gives you the name of the star in that position, ‘Regulus’.