When it comes to subjective questions (short answer, essay, etc.), I have to be a little more creative. The way I like to do it is to grade a few different students' papers first to calibrate. Then I start to make piles like you can see here - organized from best answer to worst answer. Then as I keep going through the stack of exams, I'll sort the new papers into a currently existing pile, or make a new in-between pile if necessary, and make sure that I keep answers of similar strength in the same score range. I re-sort all the papers for each new subjective question to make sure they are all graded as fairly as possible. It's definitely a lot of work (and makes the living room quite messy!), but I do think it helps me to be more objective as I grade.
How do you strive for objectivity when grading subjective questions?