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.