The bottom line is, there's more to a visual art/sport than just technique, and it's important to take care of the aesthetics. Here are a few tips that I've picked up, whether through subtle suggestion, or by being drug up to the front of a workshop as an example of "what not to do".
1. Dress appropriately - Ladies, what you're wearing DOES matter. And I know that sucks. But shiny dresses in open will get you more direct visual real estate in a 90-second round. A "heavy" dress in standard sways more and demonstrates your movement, and it's easier to focus on your Latin motion when we're not worrying that you're about to pop out of your neckline. Guys, dance pants will ALWAYS look better than business slacks. Tight sleeves make better lines than fluffy. Don't wanna buy a ballroom shirt or suit yet? Go get a 1MX from Express and spend an extra $10 to get your vest fitted. Oh, and at least sharpie out that Under-Armour logo until you actually buy a real shirt. Dressing like a serious dancer may not make you a serious dancer, but dressing like a slob certainly won't help convince anyone.
2. It's a visual sport - Guys - name one of the top 6 leads in any style with facial hair?
"Bryan Watson! Soul patch!"You are not Bryan Watson. Get rid of it. Also, a haircut would be nice.
Ladies - dancing standard? And you think your hair looks cool when it's down? Well, Edita's hair looks awesome when it's down, but she still puts it up for comps.
3. Get in the way - Judges don't really get to see each other all that often. And they have inside jokes that only a select few would understand. So they want to stand together. And no, they don't want to walk around all day to find your number. Check this out:
90 seconds / 12 couples = 7.5 seconds/couple
4. Smile - This is not about warm fuzzies. Judging SUCKS (or so I would imagine). It's gotta be like watching a kids' soccer game for these guys, except half of them don't even have a kid on the field. So you gotta at least let them know that someone's enjoying it. Syllabus dancers, particularly across multiple styles, you think they haven't picked a couple of favorites by hour 1 of 10? A smile can often get you an extra mark from a judge who needs another couple to call back.
5. You are not great - Until someone else writes a Wikipedia article about you or you get asked to showcase in another country, guess what? These judges aren't going to be "blown away" by you - so don't act like you will. Walk onto the floor humbly [arms down!] and don't take too long on your bows. Behave when you walk on and when you walk off. It's a sport with a culture and a pecking order - know your place.
6. They're playing music for a reason - The most professional step, if danced off-time, is a VERY BAD "holding still". If you don't intend to follow the music, you may as well take up gymnastics or martial arts. Watching someone dance off-time is like nails on a chalkboard for a seasoned dancer.
7. Knowing the move isn't the point - The reason there are more advanced steps as you get better is NOT so you can demonstrate, "Lookit! I did it without falling over!" The point is that more difficult steps allow you to demonstrate more technique in a shorter period of time, as well as a few advanced elements of technique. And oh, believe me, the judges know EXACTLY how well you know each step. Doing 5 things wrong to do 1 thing "cooler" won't help your marks. Stick to what you know well. That's not to say don't take risks, but try not to step too far out of your comfort zone [no pun intended]. Judges want to mark you - don't do something visually offensive that gives them a reason not to.