With 5000+ markets what strategies and tactics have you found useful to pinpoint your submissions and find new markets to publish your work more efficiently than Duotrope's basic search function?
Some of this depends on what type of writing you do. Literary-type writing (poetry, fiction, creative nonfiction, hybrid) is probably easier to narrow down — or else I have a better idea about it — than articles of an informative nature one published, say, on the internet or in niche magazines.
Your first step is to narrow your writing down into the smallest possible category; if fiction, is it sci-fi, young adult, mystery, romance, etc; if poetry, is it formal, free verse, humorous, experimental, etc; if nonfiction, is it memoir, research, lyric essay, etc. Duotrope has a pretty good listing, but you need to check out publications yourself. The question to ask is, do you like what you read there? Then your taste runs close to the editors, so consider that venue. Then, does the type of work they publish seem similar to yours?
Don't be afraid of trying more daunting submissions. Some recommend collecting rejections: aim for 100 in a year. That will keep you busy, and odds are you may get an acceptance, maybe a number of them. Also sometimes editors respond with comments even for rejections. This experience can help you assess future submissions. Or if this all seems too time-consuming, check out Writers' Relief which you can google; they offer submission services and assess your work and can advise as to where to send it for best results. They charge for this, but some say it was worth it. I'm more of a diy type and also use Facebook to network with publishers and editors and have gotten placements that way, but it's not for everyone.
If you're looking for journals for publishing stories, go to your bookshelf. Pull a story collection by your favorite author. Somewhere in that book you'll probably find a list of places where these stories have been published before. If your writing is like theirs, then this is a good starting point for you. Repeat with the other story collections on your shelves.
Once you have a list of journals, get your hands on as many as possible to verify that they publish work like yours. Then submit with confidence. Good luck.
(I don't know anything about markets or Duotropes but this technique has helped me put together a spreadsheet of journals I'm now sending work to.)