Do you ever hear a household trick and think, "That's so handy! I should try that" and then promptly forget about it? It happens to me all the time.
Well, just now I was struggling with my dull scissors as I tried to work on my embroidery and a light went off in my brain; I remembered that at some point I heard that if you cut aluminium foil, it sharpens scissors. I tried it and it works! They're not as good as new scissors, but certainly better than before.
If you've got dull scissors, try cutting foil. It's cheaper than buying new scissors or even taking them to get sharpened at the store.