I cut scrap paper into approximately one inch squares and write numbers or letters and pin them on the pieces or sections of my project. Then I pin them on in the upper left corner. I had used flower pins that I marked with a sharpie but didn't care for them and went back to the scraps of paper. I like the idea of the sticky dots also. But, the bottom line is that it is essential to keep sections organized.

Several years ago I bought a large bag of little plastic numbers at Hobby Lobby. I just use them with safety pins for numbering my rows.

I was gifted a set like Sandy I made and I loved them so much I have made sets for friends. Got the numbers at Hobby Lobby....I think Michaels has them as well. I thought about the pins I saw at a quilt shop but they were really pricey! I would rather buy fabric for sure!!!

Prism, I just ordered some Clover flower head pins b/c mine were dull. Well the new ones are dull too! I'm disappointed.
They aren't numbered though. I've never seen what you're talking about.

I slipped number beads on a flat head pins and secured it with a spot of glue. They’ve held up well, but I prefer slipping number beads on a small safety pin and using them. I close the safety pin when I remove it from the fabric and they are ready for the next time.

I use sticky notes on quilt blocks too! Attach with a piece of tape across the note so it doesn't fall off the block. Sometimes I add an arrow to show the top of block so I don't get it turned when stitching.

Love the idea of sticky dots too.

I have the Marilee numbered pins (I think M*QC sells them) but I also have made my own. I purchased a box of pearl corsage pins then glued crystal beads with numbered and lettered plastic beads onto the pins. Some patterns refer to pieces by number others by letter so I use both. I prefer the homemade corsage pins as they’re longer and secure more pieces together. Plus they’re fun and pretty too! Great gifts BTW.

I cut up mailing labels into squares and number them. They don't leave residue on the fabric and are economical.

I bought those little sticky dots people use at yard sales, etc. I put one on the front and back of a flower pin. If it did not stick well I used hot iron. Then I number these.

I use those flat plastic doohickies that close bread bags. I number as I like (usually 1A 1B ...for the first row and then 2A 2B etc for the second. If I lose one, easy to mark a new set with my sharpie. I pin thru the slot where you wedge the bag. Here is a picture...