A few things that I have done:
1. Add one or two nice light fixtures in highly visible areas. They don’t have to be incredibly expensive, but more than just the basic. I’ve done this in dining rooms, stairwells, etc. and have found it can really make the space feel higher end.
2. Personally, whenever I walk into a home that smells like candles or freshly baked goods, I always wonder what they are trying to hide. I’d much rather have the smell of fresh paint or flooring.
3. Fresh flowers always dress up a space, inside and out.
4. Give extra attention to the things people will touch (hardware, faucets, etc.). You can tell when something is cheap vs. well made.
5. Beyond that, I would spend time touring other houses for sale in the area and see what features pop. And also think about your local market and what appeals to buyers there. For example, I live in an area with fairly low utility costs, so I don’t think a Nest thermostat would give me any added value. However, surround sound in a basement rec room might! I’ve also considered installing a built-in vacuum pan in areas that appeal more to families. They are around $150 these days. It really depends on what demographic your home will appeal to.
Good luck!