I made these for a quilt swap. I managed to find an eBay seller that sold the beads already sorted into A-Z.
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Like the other posters, for numbers I drew them on to pink flower head pins.
When I remove blocks from my design wall I remove them in order, by row. I number that row whilst still on the wall and always move from left to right with the last block on the bottom. I then secure each row with a Clover Wonderclip.