How I organize my blocks using just 3 pins.
 

For pins, I have some that have an arrow on the top to indicate which part is "UP" on a block. They really help me keep from turning the blocks the wrong way when piecing. The other pins I use on my design wall are the flathead flower pins in yellow. Then I take a marker and write numbers on them. These I use to indicate positions of rows and blocks. I also take some of these and write letters on them, so I can mark a block with just three pins. One for it's row number and one for it's position in the row. If the top of the block isn't easy to tell, I add a 3rd pin with the arrow pointing up to the top of the block.

A block would be marked with, for example, a pin that has "A" on it to show it's row, and a pin with 1, to show it's the first block in the first row. And of course, the "UP" arrow pin when a block needs to be placed in one direction. Some blocks are the same on all sides, in which case you do not need an arrow pin.

I keep the pins stuck in the flannel of my design wall so they are handy when I need them.

You'd think I would never make position mistakes with this system, but when the fibro fog comes in, I will still get things confused. LOL

Good you found something that works for you.

I use washable school markers to write on my blocks. I continuously mark all the numbers on blocks. I then go back and number each row. Usually I don't mess them up.

Great idea.

I use the small size sticky note. Make an arrow pointing up and pin to the block. I also have those number pins which help keep blocks in order.

Chain pieces get a pin on the seam line just to match sure they are stitched on the correct side.

I tried the post-it notes but had trouble keeping them attached and would end up pinning them on anyway, so I thought, well, why not just use the pins.
I have not seen the pins with the numbers already on them, I wrote the numbers and letters on mine with a permanent marker.

I do the same with pins. Keeps me from having to unsew and that's a good thing.

Sometimes I will put a safety pin at the top of a block. I also safety pin a place that needs mended on clothes so I don't have to relook and relook and......

I need to create some labelled safety pins. Typically I use straight pins, but it seems I'm always sticking myself with them. Plus I've had them fall out on occasion, probably because I over-handle my blocks.

I have some decorative pins that I used a sharpie to put numbers on. I always place them in the upper left corner of a block. I use them to label the rows. I like your idea of marking the position in the row too. I don't need an up pin as if I see the pin in the upper left corner I know that I have the block in the proper rotation.

I cut up a wall calendar page. Then I just pin through it. I used the blank squares for other info I need like top, right, left. I just keep them paper clipped in order in a snack bag when I'm not using them. Since I usually have multiple projects going, I never run short....just cut up another month. I do always pin them in the upper left corner for orientation.

I have numbered pins and I always pin through the top left hand corner.

I have tried several of these ideas and, for some reason, don't stick to one. They all do work.

I was watching a YouTube video by Jordan Fabrics this morning and she used the peel off clear address labels. She wrote on them first and then peeled them off and put them on her blocks. I tried painter's tape once but would sometimes iron over it and got a big mess! So I am not sure if the labels would work for me. :) I might give it a try though.

I took art foam sheets and made little squares with a set of numbers in one color and a set in a different color for the alphabet. I punched two small holes in each for pinning, and wrote on them with a black sharpie. Now, all I do is either use a straight pin or safety pin to attach them to my blocks in rows and columns. In between uses, they live in two small baggies that are kept near where I am currently using for a design wall (bed, table, floor, etc.) since I don’t have an actual design wall.

madamekelly, perhaps you can use the kind of design wall I have. It's cheap, easy and can be taken down with ease if you don't have a permanent place for it.
I found 3 pants/skirt hangers with the clips that work like clothespins, not the kind that slide. My DH put 3 screws in the wall up by the ceiling. Mine is in our back hallway, but you could do it over a closet door, etc. I hang one hanger from each screw and clip flannel backed plastic tablecloths from the thrift store to the hangers. I usually can get the tablecloths for 1-2 dollars, and they last a very long time. My current one is 2 years old. On my wall I use 2 tablecloths at a time to give me a larger area, but for most things one large one would work.

When you are done using the wall, you can simply take down the hangers, still attached to the tablecloths and fold the whole thing together. You can even fold it with blocks still in place if you need to take it down before you are done. The three little screws are not noticeable, especially if you paint them to match your wall.
Use screws that will reach into the wood framing, rather than short ones that end up only in the drywall. The weight of the setup and your fabrics will pull the short ones loose.

I like the Alphabiddies from Fat Quarter Shop. They work great, no pins needed.

I use green painters tape and a sharpie. It works so well. I have not misplaced a block since using this method. I only use pins when I have to. I always seem to poke myself with them.