How should I make my car look better for showing?

Take it to a good detailer

Make sure they use clay bar before waxing too. That will make a huge difference.

Take it to a car wash first. Then, detail it yourself, just a bit every day so you don't get tired of doing it. After a few days of making sure you got all the dirt and dust, take pictures of the car from all angles and several pictures from the same angle, and take them out in the gleaming sunlight so the car will appear bright and shiny. Then, turn the car around 180 degrees and do the same thing again. After you download the pictures, examine them on your computer screen and select on the best ones to post with your car. That's what I've always done, and it works like a charm. Oh yeah, do a little creative writing when you do the car's description.