Description is best when it involves all five senses. Especially smell, if its appropriate. The trick is knowing how much to reveal. Skimp on physical descriptions of people. Use the mind's eye to see the key details and write those down. Leave the rest to be filled in by the reader.
I learned this one in 10th grade English, and employ it myself. When I have to write a description of something, I try to run down the list of five senses. The two most underused ones are smell and touch. Taste usually doesn't apply, unless you want to have someone lick the mystery thingamajigger for some reason. Smell is the most important because it causes the most visceral reactions, and it's not used very often, so it's a great dynamic. Smell is the most powerful trigger of memory, so it helps connect with the reader.
The second part involves the theory of "Writing is telepathy" again. People don't want to read very detailed descriptions of things. I often dread reading a long paragraph. Often, they contribute nothing to the story or plot, but I still think they're essential for creating the picture in the mind's eye. Books I read these days have next to nil for people. Usually, it's hard enough just trying to get what age they are.
For example, in Blood 2, I have no description about what the main character looks like, because I had no idea what the main character looked like. But through the writing, there are a few times that I made other characters mention that he looks like he hasn't gotten enough sleep, so I assume that he has sunken, bedroom eyes. Maybe he looks like the guy from The Cure. I also imply somewhere that he's skinny. I don't really know what I did that. But my point is, I never stop the narrative for a description of what he looks like. It comes out through the rest of the story. Although it would be a good idea to put such statements near the beginning of the story, and not reveal that he has a clown nose super-glued to his face at the end.