Thanks to "Bobblin the merchant" for this thread idea.

(I'll write up my own thoughts on the matter at a later time, just wanted to get something up in the meantime.)

I'll kick this off with a proposition that when describing places you should just roll through the senses that are relevant to the character and consider each one in turn and whether there is something worth writing about... and the answer is that there probably is. However, remember that not every character is human and limited like us so the range of senses may be wider.

For environments I have this checklist in my head:

• Sight is the usual place to start because humans are visual creatures (unless its a lightless cave at midnight during an eclipse with 100% cloud-coverage while under the effect of a Darkness spell).
  Think about the variations in colours, shapes, sizes, and textures. Things are not always all the same. The extent to which it might be natural or artifical. Which things are clean or dirty or burnt or shiny or oily or...
  
• Hearing is next, and think not just about the obvious sounds but the general environment.
  Are there buzzing insects, sounds of some activity, far-off trickles of water, rumblings from a distant storm. What did you describe in the environment that they can see and could it contribute to the local soundscape? Now what about the things that they can't see but you know are nearby?
  
• Smell would be next and I find this really evocative for setting a key scene up. You need so little writing to suggest so much.
  Typically there would be a dominant smell (which could be no smell but this is unlikely) but there may be a conflict between two smells which different characters pick up on, or an extent to which a smell is localized in part of this place.
  
• Taste and Touch are less likely for humans to pick up on in this first description. This could be where they go after they interact with things. But what about the temperature that they feel? And its not just hot and cold, but humid or dry as well. Is the air moving or still.
  
• Sixth sense/Intution... is there a feeling that some of the characters might have. Is it alien, or strange, or familiar or...

First, make sure it's worth bothering.

People generally don't gain a very good mental image of something that is just described to them. They do a little better when they actually see it. But D&D players are infamous for not recalling details that would have been obvious to someone actually there.

So, if the players don't need to have a memory of the thing, take it easy and don't sweat it being to descriptive.

If they really do need to have a sense of the thing, there's something better than description or even drawings: collaboration.

People are very good at retaining things that they themselves had a hand in creating. Most people know the ins and outs of their character, if they made it themselves or helped make it. They tend to remember their magic items, for instance. What they tend not to remember are random items they DM placed for them.

So, the way to get to where a scene is memorable, involve the players. Take the bare bones of what needs to be in the scene and ask the players leading questions to fill in the details.

"The first floor of this abandoned tower has an interesting smell, both pleasant and unpleasant. What does it make you think of?"

"The captain of the guard has a noteworthy voice and off-putting facial hair. Describe it."

"The enemy camp is awash with the noise of soldiers recovering from and preparing for combat. What are a few sounds that you notice?"

The DM can, in addition to asking leading questions, seed a detail or two, or offer suggestions, if needed. Then, whatever the players say, add to it. Build off it. It doesn't have to go anywhere or mean anything but to have one's idea built on associates it with some pretty good feelings and will really help lock the overall impression in their minds, even if only a small number of details are actually stated.

Remember the species you're describing to as well. Humans get most of their information through sight, but most animals use scent - and some rely on hearing. If you want to offer your werewolf insight into something, they're probably going to try view what it smells like as more important than what it looks like; similarly, a lot of humans make the mistake of following people simply because they're good looking without actually listening to the drek that comes out of their mouths.

There might be exceptions to these rules, depending on the context, but:

You’ve probably heard this one before: “Show, don’t tell.”
Think of what you’re trying to convey, then think of what descriptions would convey that point.
Instead of “she looked happy,” maybe “she was smiling widely as she skipped and hummed.”
Instead of “there had clearly just been a bar fight,” maybe “bloodied patrons fled, dragging unconscious buddies with them, leaving behind tipped furniture, shattered mugs and a few teeth.”
If you find yourself saying “she looked happy, with a beaming smile etc.” maybe skip the “she looked happy.” Don’t use more words than needed, don’t be redundant (unless maybe you’re really trying to emphasize something).

You can tell a quick story just with descriptions, without explicitly stating what happened. (Similar to above.)

For characters, I think facial expressions should be pointed out. It can give a quick idea of their mood, attitude, who they are as a person, which is often more important than other details.

I try to think, “what are the first things someone would notice about this person/place/thing?” and work down from there. Are they particularly tall or short, wide or thin? Glaring marks or noteworthy clothing?

Avoid being over detailed, instead aim to get a general idea across.
This might involve keeping things simpler and cutting excess details you had in mind.
As someone mentioned, players probably won’t remember every nagging detail, so there might not be a point in the first place.

Depending on what you’re playing on (tabletop, thearte of mind, roll20, Discord, forum), you might be able to just use pictures. (Granted probably accompanied by some description still.)
If you’re going to use pictures, you’re probably better off using them right when the thing is introduced, as opposed to afterward. This is because players (and you) will form their own mental image of something, and if you introduce a picture after the fact, it’ll probably conflict. (I hate when I think of a character or setting, but then can’t find a suitable picture.)