I am imagining something similar to the original "Twilight" cover that has a black background with a simple image. For my book, I was thinking a black background with the single image of a glass locket/necklace with a blue flame that burns fiercely inside it. The necklace is key to the plot and I'd like it to look almost sinister. The mood should be 'witchy' and gothic.
The ideal size of your eBook cover art is a height/width ratio of 1.6:1. This means that for every 1,000 pixels in width, the image should be 1,600 pixels in height. To ensure the best quality for your image, particularly on high definition devices, the height of the image should be at least 2,500 pixels. Ideal dimensions for cover files are 2,560 x 1,600 pixels.
Note: The minimum image size allowed is 1,000 x 625 pixels. The maximum image size allowed is 10,000 x 10,000 pixels
Your cover image must be less than 50MB. Try to avoid compressing your files. This can affect the quality of your cover when displayed on reading devices. For the best results, images should have a minimum resolution of 300 PPI (pixels per inch).