Stick with the past tense, even for descriptions of currently held positions. This is the biggest mistake you can make, and it's the most common one it seems. The resume is no time for modesty. When you're just starting out, your resume should not be more than one page. Avoid lengthy descriptions of what you've done and how it's relevant.
Managers like to see activities listed for several reasons.
Activities show that you're a well-rounded person who has interests, who can maintain interests while busy with other things. This is a good place to accent your skills that aren't covered by work experience. Format Your resume should be easy to read. Categories Establish levels of organization. See the samples for clarification.