The sense of smell is often ignored, which is tragic. Even if you don't have a strong sense of smell (I don't), there are certain universal smells that can be conveyed with just a few choice phrases. Consider a passage describing the smell of burning popcorn. There are very few people who don't know just how bad that smells. And telling someone about it in detail creates an instantaneous reaction. While this particular smell is usually something people would prefer to avoid, there is no doubt they could imagine standing there with that aroma and feeling repulsed.
How about a huge flowerbed full of roses? A passage describing the aroma as a slight breeze flies across these fragrant stems is sure to evoke any number of emotions for the reader. Whether they like the smell of roses or not, they'll see these flowers as realistically as if they were actually standing among them. And then they're captivated by our world, eager to see what else unfolds.
When was the last time you described the smells in your world?