I can't seem to get my hands on the APA SOP book. Is that the best way to learn/evaluate my birds? The SOP is the only way to evaluate birds, but there are many ways you can learn to evaluate birds. You can go to a show and ask judges or breeders to walk you through it. You could even invite someone over to walk you through your birds. They might be happy to help mentor you. They might not, but they will be honored that you asked. You can get information online. One thing I did as an aspiring artist (and personally I don’t know anyone else who did this) was look at the standard and a picture of the breed and then I’d draw not what I see but a perfect example of the breed based on the description in the Standard. This helped me picture the bird better in my head and really ingrain that description in. I think it worked since I judge fairs now, and I’m not bad at it. Plus now I can draw really well and I couldn’t before so I think I killed to birds with one stone.

But as you can see, everyone learns in different ways.
Would I make posts here? (That would be a lot of posts! I have like 50 birds right now!).
I'm trying to narrow down which breeds I enjoy working with the most. I'm really liking Ameraucanas, but are they too common? Ameraucanas are the most common breed I see sometimes, but there’s nothing wrong with common. After all, if everyone thought it was too common it wouldn’t be. But I can see why you don’t want to. I like novelties myself.
I want to work with birds that aren't super common, but have really docile, easy going temperaments. I originally liked the deathlayers, hamburgs, campines, but I think they're a bit too flighty for me.
Any suggestions on less common, friendly, personable birds?
I’m not sure what utility qualities you prefer. Delawares and Buckeyes are two breeds I find to be very friendly and uncommon. The main difference is that Delawares can be pretty stupid, at least the males, and Buckeyes are very intelligent. Amer, my username, is kind of an artifact because I thought I was going to love Ameraucanas, but for all their outward flairs, they turned out to be as bland as broth personality wise. I haven’t raised many rare breeds outside of the American class that were friendly, lol. Anything pretty is bound to be more high strung, or just something that looked like too much work for me to try. Personally, I own bantam Buckeyes and d’Anvers for their personalities, hardiness, and looks, but I don’t know if bantams are your thing. If they are, there’s Japanese bantams.