I'm designing a mobile screen (iPhone and Android) for adding a review; my sense is that the 'Attach Image’ button is not placed correctly or shouldn't be as big button as 'Submit Review'. Please see the image below.
How can I make this 'Attach Image' button look better?
I think it's a hierarchy problem, you are creating a couple of subfields for text editing and two CTA buttons at the same level, when one of these buttons belongs to one of the previous areas. Beyond the use of color or size, I suppose the user must have clear that one button is for the general review action while the other only belongs to an internal part of the edition.
An exaggerated example:
A single total edition field
A submit button
There's a place for thumbnails and more photos can be added:
"Attach Image" is machine-speak; it's more or less how engineers talk about the function that your button is doing, and this looks like an app that is enticing consumers to share.
You could try more user-friendly verbiage such as "Upload Photos", or drop the verbiage altogether and use an icon. The bold purple of your Attach Image button is competing with the red Submit button, and it's not as important of a function, so look at ways to subordinate it. Yelp has a good example of this.