2. Exposure has to be perfect. Underexposed and overexposed photos are eliminated, always.
3. Composition. Learn the basic rules of composition and apply them. The Rule of Thirds, Leading Lines, Framing, Curves, Symmetry, Patterns and Background are just a few of the terms used in basic photographic composition. If you don't understand them, you are just experimenting. That's fine, and I encourage experimentation. But, it rarely gets you anywhere in a photo contest.
After using 1-3 above, in taking a photo, the next two tips come in handy when you submit a contest entry.
4. Title: Give your photo a title that gets the judges attention. I get away with just putting a critter's name on a wildlife photo, sometimes, just because it's something a judge has never seen before.
But, if I shot a picture of a cat, I wouldn't title it "Cat". Let someone else do that.
5. Caption: Try to come up with something interesting to say in your description of the photo.
Many contests base their scores on the five tips given above. Some grade the photos entered by awarding a possible 20% of the total score for each of those five steps.
That means, if you took a perfect picture, as far as focus, exposure and composition go, you could lose out to the folks who had the best titles and captions. Forty percent of your score may not even depend on what came out of your camera. Another photographer can beat me with their choice of words.
That means I have to use my brain, too. OUCH !
Time permitting, I will add more about entering photo contests to my PHOTOGRAPHY TIPS.