Make your elements appear more defined
Use Multiple Drop Shadows, or a very subtle border (just a shade darker than your actual shadow) around certain elements to make those elements appear a little sharper, more defined, and help avoid those muddy shadows.

Creating long-form content? Give 20pt, and up a try
#18pt is sooo last decade.#

Your shadows are coming from one light source right?

Improve Contrast between Text and Images with a subtle, but simple Overlay
Depending on where the text may be positioned over your image, you can either opt for a tried, and tested full image overlay, or a more subtle (bottom to top, or top to bottom) gradient overlay to achieve a simple contrast between the two elements.