Choose the right words
Readers don't want to work hard to envision the setting, you have to do that for them! If you choose you describe things using words such as "big", "happy," or "fun", you have basically written a one-way ticket to the paper shredder. Be bold! Use words that show the reader exactly what the character looks like, or how large the dinosaur is.
Check, check, and check
Publishers like to be in charge. So when a contest or magazine tells you what they want to see, you're going to have to give them what they want to see. Twelve point New Times Roman font is the standard text format for most submissions, so if you are not
No plot-- a huge problem
Don't be this guy!