I should be able to see loops and conditionals and other control structures without focusing too much on the code itself. I like descriptive variable names, but don't go overboard. Variables that are used to index can be one letter. Anything else must have a readable, understandable, descriptive name. If I can't follow your code, you're pissing off the one who is grading you.
Comments Get into the habit early.
All coding classes require extensive use of commenting. Makes my job grading easier and also makes your job of going back and finding errors easier. Needless to say, a good commenter has the right idea.