Art Direction can be difficult to demonstrate what you actually do.
It's so collaborative, it's rare that just one person sees something from beginning to end. Here are some examples of how I give notes and communicate visually with fellow artists.

Marvel's Spider-Man 2 was one of the most high profile projects I have ever worked on, with many parties interested and invested in it's success. The majority of the credit must go to Insomniac, but these are the type of notes I give at Marvel to help even the best artists push a little further to get the best product possible.

...I even got to art direct a Wheaties box!

When working on the key art for Spider-Man 2, we went through many rough iterations. We at decided we wanted the key art to continue the same design beats as the previous two games. The vendor gave us the rough models, then I did a paintover to explain how we would like the models pushed, creating directionality and dynamic energy in the image.

Once we had the poses in a good place, I began giving notes on the secondary forms. We had to let the vendor know that it was ok to push the models to create a compelling image. We asked for certain muscle groups to be emphasized and for the symbiote goo to move up the form in a way that added to the image, integrating into Peter's arm in a cool way.

There are also lighting and vfx notes. Letting the vendor know what we expect and what is ok to push and emphasize.  

These are various marketing art and production notes.  I had the privilege of working on the special edition ps5, it was a very quick turnaround as they needed to get the production line ready to go so they could have them out to coincide with games ship date. Just some quick notes to the designers on symbiote tendril shape language.

There are also some production notes regarding the special edition statue, Hot Toys,  skins and certain in-game props. These are but a sample, but it's very much a process of working with amazing artists and helping them find the right design for the needs of the product.

Sometimes, I'll make notes that are too late to implement, like the Venom marketing art Paintover below. I find that Art Direction is a game of choosing your battles. Sometimes things go out that aren't 100% what you envisioned, but the trick is to make sure that nobody notices!