I really do put a lot of emphasis on students being able to express their ideas very clearly in writing. If students have been able to write about their work, along with being able to do their lab work competently, they know they have performed well. I am enthusiastic, inspiring and knowledgeable about my subject. I generally expect a lot from my students and hold them to high standards. Student evaluations tend to confirm my perception of my teaching.
Students do well if they come sincerely interested in learning something.
Students who don't have the maturity to work on the subject don't do well with me. Maturity and sufficient background are the major considerations for me. I want people to be mature enough to complete the work.