Most high school juniors are visiting colleges this year to try them on and determine the best fit. They are also thinking about majors. However few students do more than that in 11th grade. But there are other equally important tasks that are best accomplished prior to the fall of the senior year.
Reading books not required for class is essential for high school students. The most diabolical college entrance question I saw this year was: "List the books you have read in the past year and put an asterisk by those not required for class assignments." Most students I worked with had read very few, if any, extra books. They have a very good excuse, limited time. Summer is coming and that is the time to get this done. Waiting until fall makes this task impossible.
Writing essays now can help students write excellent essays in the fall. This is a writing form not emphasized until college. But colleges expect students to be able to write a stellar essay to get in. Not fair, but that's the way it is. Fortunately, there are great books on writing essays and English teachers can be of great assistance.
Students need know their interests, talents and goals to compete well for college admission. Interview family, teachers and friends about their impressions. See a counselor about taking an interest inventory. Start writing in a journal or diary on personal thoughts to get insights to use later.
A resume of activities, volunteering, employment and accomplishments is essential to college admission competition. Completing one prior to the senior year will point out deficits and strengths. Any areas found lacking can be fixed-if the deficit is found NOW.