Edward,
Being on time (or before), greeting students, being approachable to ask questions. These convey the teacher cares, and they're simple to do and every teacher is capable of doing them. But in order to do these (simple) tasks, the teacher has to have all their stuff in order, copies made, materials and resources gathered, daily plan mapped out - in short, ready to rock and roll. This, coupled with student access to the teacher makes for good student/teacher relationships, and of course, that helps in the learning process.
Barry Westling