Time
It research and submission can be very time consuming when you first begin, or if you only do these things on a now and then basis.
If you write first and look for markets later, it can take far too much time. I always find the markets first, and write the stories with markets already in mind. I have a primary market in mind, and at least three or four secondary markets in mind. I keep a database of markets I've written for, and markets I want to write for. I find these markets in all sorts of ways, from databases such as Writer's Market, duotrope,
http://www.duotrope.com/index.aspx and Ralan,
http://www.ralan.com/ and from online research.
I spend no more than half an hour per day looking for new markets, and this is usually plenty.
And unless a deadline is pressing, I do all my story submitting at one time, one day per week.
My typical workday is spent 50-60% writing, and 40-50% reading. And with deadlines pressing, it's a simply matter to skip the reading and write 95% of the time, while still spending all the time I need for finding new markets.
Kate is right. It's about being organized, and building a market list over time. And it's a matter of knowing who you're trying to sell to before you write the story, rather than after.
