Originally my husband and I had brainstormed a long list of characters and just pulled from that. We were just trying to find enough characters to fill all the slots. At this point the list consisted of primarily characters that we liked (which means it was at least 75% Bleach, Full Metal Alchemist, Final Fantasy, and Clamp). This more basic goal changed. After the Major Arcana and the Swords sets were finished, I started reanalyzing the character list I was using to assign slots for the set. Instead of keeping to the original list, I decided I'd rather see how many different series I could represent in the set. There are some cards from the Majors and Swords I would have changed out, but they were already finished, and I wasn't about to touch that. So, I highlighted all the characters from series I had already drawn from or had multiple characters (exceptions being the Kings and Queens). I sat down with a committee of friends and we rehashed over the remaining three suits.
Some characters stayed the same--for example the King and Queen of Cups, Sakura and Syaoran from Tsubasa Chronicles. I already had Fai as The Star and Kurogane as the Eight of Swords, so Sakura and Syaoran were high on the list of characters I wanted to take out. I spent a lot of time looking for replacements. However, the King and Queen of Cups represent an emotionally mature man and woman--anyone familiar with anime can relate to how difficult it is to find one character with that quality, let alone two from the same anime. And so, Sakura and Syaoran remained the Queen and King of Cups.
For a lot of the slots, we did find adequate alternatives. For example, the Seven of Wands was originally going to be Light from Deathnote. He had been highlight since I had already drawn L as Death. Several suggestions came up while discussing this card. The first replacement for Light was Kamina from Gurren Lagan. Kamina eventually moved into the Three of Wands (leads by example) replacing Hikari from Magic Knight Rayearth--it was determined that I had way too much from Clamp even if they were spread out over at least four different series, and I'll admit I'm guilty there. What can I say, I'm a big fan of Clamp's stuff. Heero Yuy was suggested along with some explanation for how he fit the card from a couple of friends who had seen Gundam--as of yet I still have not watched even one episode of any version of Gundam.
In conclusion, we tried to put a lot of variety into the Anime Tarot set. The choices were, in the end, still limited by what we (myself, my husband, and a couple of friends) have seen--I will be the first to admit there are many anime series out there that I have not even heard of. Then, the selections were also affected by my personal tastes--when there was a choice between several characters, it frequently boiled down to the one I liked best, or wanted to draw the most.