What should go on the activities list?
Everything that took real time, ordered by what matters most to you rather than by prestige. Paid work and family responsibility belong there and are consistently undersold. Use the character limits to say what you did and what came of it, not to name the club.
Order is a message
The reader starts at the top and forms an impression fast. Put the things that genuinely occupied you first, even if a lower-status activity beats a higher-status one. A student who worked twenty hours a week should lead with the job.
Include the things students leave off
Paid employment. Caring for siblings or a relative. Contributing income to the household. Serious hobbies pursued alone. These are routinely omitted because families think they do not count, and they are frequently the most revealing entries on the page. Independent, unglamorous commitment is exactly what readers are trying to find.
Write descriptions that carry information
The character limit is tight, so cut the words doing no work. "Member of Key Club" says nothing. What you did, at what scale, and what changed as a result says something. Numbers help when they are real. Skip the adjectives and keep the verbs.
Fewer, deeper
Ten slots do not have to be filled. Four activities pursued seriously read better than ten joined for the list, and readers are practiced at spotting the difference. Padding costs credibility on the entries that were real.