Planning on teaching a computer nostalgia class? 
It’s partially muscle memory, so I hope you actually get to type it too… that said, in order to just get the basics memorized, I’d use one memory palace per category.
Load and Store (one palace)
LDA, LDX, LDY, STA, STX, STY
L## is load and S## is store; ##X and ##Y uses index X/Y, respectively instead of memory. I’d say the mnemonics are pretty decent actually. Plus, the Addressing Modes for X and Y are similar except for the X and Y part.
…not sure about the similar complexity, this entire category in total looks less complex than just LDA itself:
Branch (another palace)
BCC, BCS, BEQ, BMI, BNE, BPL, BVC, BVS
I have a post here explaining how to memorize the book mentioned in the post. You can use the same approach for your purposes:
So, first place all the categories (Load and Store, Arithmetic, Increment and Decrement, etc.) in front of the stores and then place their instructions inside their respective stores. Lastly, if you need to store the addressing modes on a route, do it on a separate one… just like I mention in the above post as far as Jonathan Edwards, Benjamin Franklin , etc.
For the categories, use whatever makes sense to you… “Load and Store” could be “Lost and Found”, “Arithmetic” could be “Asthma Attack”, etc. If you really think that the mnemonics for the instructions are not easy enough, you can use this approach to get a PAO image for each instruction.
They are conveniently all three characters long, so the first letter will get you P, the second A, and the third O. Assuming you already have a PAO system for 00 … 99 it’s a pretty quick way to get the instructions translated.
LDA (using major system codes for braille cells)
- L is 70 (KS) say KISS (the band) with some A and O
- D is 13 ™ say Tom chasing Jerry
- A is 10 (TS) say Tyson (Mike) biting ear
So with memory palace from the first link… there is a lost and found box in front of the Cheesecake Factory. You walk in and in the first location you got “KISS chasing an ear” which is the braille PAO for LDA. You should know what LDA stands for. In the next location you find a PAO representing LDX. If for either of those two you need addressing modes stored, create another route (palace) somewhere else.
Hope this all makes sense. Let me know if I should clarify anything with more examples.