I like Tom's idea. I did something similar at first, but I didn't print them out. Instead, I made a board of my irises on Pinterest, where I can shuffle the "pinned" photos around.
Now I pretty much place a new one where I have a bit of space, trying to keep in mind the colors that will be blooming around it.
I like to keep the yellows and oranges pale, so they harmonize better and yet perk up the garden. And I try to keep very multicolored ones to a minimum because though they may be beautiful as individual flowers, to my eye they tend to look mussy on masse. And so I tend toward selfs and bitones, though I may make rare exceptions. Rules are made to be broken.
If I have an iris that doesn't play well with others (but I just had to have it!), I've been known to make a separate garden for it, where I specifically plant others that are more likely to harmonize with it.
