Tips for a newbie?

The flash has also produced strong/harsh shadows in the first picture.

Hi @JorgeCano213 ,

In addition to what is said about the first image is under exposed and has no detail.

The second image displays color noise (visible on the socks and shoes) and seem to be over sharpened. You could include in the frame a little more of the ground behind the seat. It also appears you did not have enough depth of field. Zoom in to between 100 and 200% to inspect your images for errors.

Best wishes

JG

Photographer and Nutrition Author

Read these links.

• https://helpx.adobe.com/stock/contributor/help/reasons-for-content-rejection.html
• https://helpx.adobe.com/stock/contributor/help/quality-and-technical-issues.html
• https://helpx.adobe.com/stock/contributor/user-guide.html/stock/contributor/help/photography-illustrations.ug.html
• https://helpx.adobe.com/stock/how-to/tips-stock-image-acceptance.html

The first image is out of focus, has artifacts and is not well composed. You cut off part of the fingers and the picture frame in the background is distracting. 
The second image seems to be focused, but has a White Balance issue - a bit too blue. I think the composition would have been improved by backing up a bit and including more of the natural scenery. The edge of the bench is cut off.

I can't seem to edit my post but I wanted to add that the first picture was from a photoshoot I did from a monster design I created and modeled. The second picture is from a walk I had at a park and I decided to take some scenic shots I also modeled in the picture aswell.