Remember that high-quality photos are critical to the success of your listing. 
 
Photos should be: 

Full HD high resolution, try and get them sharp and well lit.
Minimum 1024 x 768 pixels or higher
Maximum file size of 2MB 
Format of JPEG/JPG, PNG or GIF  
Upload approx 25 good photos depicting the property at its best.  Your main photo should showcase your best feature e.g. pool, view or patio.
For faster upload, try uploading no more than 10-15 at a time.

Try to avoid:

Low-resolution, blurry, or too dark 
Black and white 
Inappropriate 
Watermarked 
Copied from another listing 
Oriented incorrectly 
Unrelated to your property or area 
Blank or duplicated.