But something that I think the DMG may even mention (or possibly DMG2, it seems like the kind of thing that would be in DMG2): it lends verisimilitude and consistency to the world if you always describe the same sort of potion the same way.
So, in the same sheet as my list of items, I've begun to create a master list of potions. Every time anybody finds a potion that isn't already on the list, I'll add it to the list, and henceforth describe all of the same kind of potion the same way. From now on, potions of cure light wounds will always be "shimmering puce".
This gives an additional way to quickly identify potions: if you've seen a potion of glibness before and it was a transparent white potion, and you encounter another transparent white potion, it's a safe bet that's another potion of glibness. There are only 900 possible combinations, so the slightly hilarious situation might arise where two potions appear identical (like what happened when Sky the drow cleric labeled several flasks of acid "healing potion"), but that's likely to be pretty rare.
To this end, I created a master random potion chart (cribbing in part from the possible potion descriptions available in Angband), which one can consult whenever a new potion needs to be described. You'll need to roll two d30s (or one d30 twice):
(Any potion described as "coagulated", "clotted", or "sedimentated" should be shaken well before use. Any potion described as "bubbling", "fizzing", or "effervescing" should never be shaken, lest it explode.)
If you want to really push the number of possible combinations up there, you can first roll 1d4: 1 = roll color once, quality once; 2 = roll color twice, quality once; 3 = roll color once, quality twice; 4 = roll color twice, quality twice. This allows for things like a cloudy, marbled, silver-and-maroon potion. Perhaps if there are two colors, that might mean they're separated like salad dressing and you should shake well before using. Or if there are two colors and it's bubbling, maybe the bubbles are the second color. There's a lot of room for improvisation.