In these of unleaded fuel, you may use spark plugs until the electrode erodes away. Every-so-often, check the center electrode for a sharp edge. As slowly rounds off, file it sharp.
Admissions officers look first at test scores, the rigor of the courses you take, and your grades in those courses. After that, they are interested in a student's extracurricular activities -- in other words, how you spend your time outside of classes.
Applicants who apply early decision are almost certain to attend if admitted. When the college doesn't have to worry about yield, it can better manage its enrollment strategy. Applicants who apply early decision have made a clear statement that the school is their number one choice. This type of institutional interest and loyalty is valuable for a college both in terms of higher retention rates and future alumni giving prospects.