I agree with everything Ev has said, but I'll add this:
Treat your puzzle as you would any other submission. Read the guidelines. Present it as you would a manuscript, using cover letter, then inclusion of puzzle and solution. As long as it's professional, the editor won't reject a puzzle based on where you put the solution.
Give your puzzle a title, as with any other manuscript. Make the title appealing and pertinent to the topic and audience.
Don't include illustrations for the most part, unless they're part of the puzzle. I've sold several crossword puzzles and have never included illustrations as the magazines has an illustrator do these. Ev's puzzles often incorporate the need for illustrations so it makes sense for her to include them, but even then, hers are using geometry shaped/based artwork through a computer program. She isn't an illustrator and she isn't trying to sell her illustrations, but her puzzles. if your puzzle needs a certain amount of illustration to convery the concept, then include it. Most likely a professional illustrator would be used to redo your illustrations.