A minimum of 2,500 words per day. I write five hours each day, at least five days per week. I break the writing into two daily sessions, one before lunch, and one after. Some days I write considerably more than 2,500 words during these five hours, but never, ever less.
During the lunch period, I eat, and weather permitting, take a long walk. Weather not permitting, I exercise some other way. Some exercise is critical to good thinking, and most writers don't get enough.
Tips? First, have a regular schedule. During this time, write. Make it a habit. Do not tell yourself you have all day to get something done. Or all week, or all month. It isn't about deadlines, it's about Parkinson's Law: Work expands so as to fill the time available for its completion.
Your schedule needs a starting time, but it also needs a finishing time. Start when it's time, and stop when it's time. Make this a habit, and productivity will go way up.
And always, always, always read everything you can get your hands on. Reading generates writing. Don't skimp on writing time, don't allow reading to interfere with writing, but make sure you read something everyday.
One of my majors was Journalism, and while some types of Journalism bear little resemblance to fiction, human interest pieces, and even some types of columns, are very similar. I learned more about writing fiction in Journalism classes than in English Lit classes or creative writing classes. It's no coincidence that some of the best fiction writers out there have at least some background in Journalism.
Use what you learned there. Saying much with few words works as well, or better, in writing short stories as in writing a human interest piece.
I assume it's the same all over, so remember what you learned about writing fast, but also writing well. We often had deadlines measured in minutes. A prof. would hand use a sheet of facts on a breaking story and give us half an hour to come up with five hundred words that could be printed as is.
Of a sheet of facts about some interesting person, and give us a generous hour and a half to hand in a 750 word column. When class ended, we had to turn in the finished piece, and it had to be good.
So when it's time to write, sit down and write. You have a piece to hand in, and the press waits for no man.
Every Journalist knows the five W's. . .who, what, where, when, and why, but those new at fiction often don't understand that these apply just as much to a short story as to an article. Who, what, where, when, and why is what makes a short story a short story, rather than just a list of events. (Though human interest is what these are all about in both.)