And here's a bonus 11th Commandment: "Thou shalt not pass out paper copies of thy slides, unless the audience speaketh not thy language."
Like the real Ten Commandments, it’s unlikely that you’ll keep them all, all the time. So ask for grace. Find a friend who can help. Two heads are better than one. Better yet, hire a designer (I do). And live by the credo: when in doubt, leave it out.