My hair is flatter on the top too, especially now as it's pretty long. My best results come from detangling my hair in the shower and then flipping my head over, detangling again upside down. I then rinse upside down, put my products in upside down and then go straight to tying my hair up in a t-shirt to plop. I keep my hair like this while I do my make up and stuff.
After I take the tee off I'll usually put some clips in at the roots. Then I leave for work and aim the car vents at my hair to dry it. I take the clips out when I get to work and usually my roots are okay and not too flat, at least not as flat as when I do everything right side up and don't plop.
Hope that helps a bit.