1. Does Stock already have millions & millions of these? If yes, don't submit it. You won't make many sales.
2. Is yours as good or better than what Stock has or does it need improving?
3. Examine your best images at 100-300% magnification in Photoshop or similar image editor. Correct images if you can, otherwise discard them.
4. Submit 5-10 of your best corrected images to Stock -- highest visual & technical quality, proper exposure, good focus, sharp details, pleasing composition. Sit back & wait for review.