It really depends on the genre.
It also depends on the type of story.
Duotrope is good, but also make a visit to your local library to see the magazines first hand. It may look "GREAT" on duotrope but come to you with a center-stapled "booklet" that looks like something a high school journalism student cranked out over the weekend. By reading current issues, you can also glean something of the style and voice (and structure) a current editor is looking for.
Circulation over 2000 is something I personally shoot for. Pick up a copy of Poets & Writers. They'll have contests, calls for submissions in the back of the magazine.
If you are shooting for genre (specifically Sci-fi/Fantasy), I'd start with SFWA's eligibility list:
http://www.sfwa.org/join-us/sfwa-membership-requirements/#shortfiction
Always (always always always X1000000000) read the submission guidelines.
Always.
No exceptions.