It behooves you to develop good relationships with a number of teachers throughout your four years of high school so that when it comes time to write a recommendation they know you both as a student and a person.
Sophomore year is the time to get serious about academics and extracurricular activities. If your freshman experience was not what you hoped it would be, don't worry; you can get a fresh start as a sophomore.
Looking at the other grades counting down the days until summer, I am envious. While they are all off on exciting adventures, nearing exciting portions of their lives, all I am feeling is apprehension. My summer? A mountain of summer work.
There isn't a lot you need to do about college admissions during your freshman and sophomore years of high school. Nevertheless, this is a good time to start becoming informed about the process. It's never too early to do that.