I started DS in October. At first, I was really working slow, sometimes taking as long as 3 hours to write one article! I'm now aiming to choose/research/write/and hit submit within 1 hour and 15 minutes for each piece. Sometimes it takes 45 minutes, sometimes it takes an hour and a half, but if it goes over the latter, I look to see what the problem is--why it took so long.
I aim for at least 10 dollars an hour gross...I figure that at least earns as much as I'd be making at a local bookstore or packy, and that justifies it for me. I look at DS as stop-gap income, the income that comes in when nothing else is available.
Tips that have helped me:
-do a quick search when choosing a title--if you can't readily find sources, don't choose it
-try to choose articles in 'clusters'...that way you can recycle research and sources (for instance, I did 4 articles on pinball machines...used the same resources)
-it helps to choose material you are familiar with, but not always the case (heck, I did about 15 articles about repairing ice makers a couple months ago--I am not handy at all, lol!)
-take a break if you feel yourself getting frazzled. Frazzled=low productivity. I'll take a break and do a house chore or have a cold drink or a snack...just to refresh.
And, this is key (for me, anyway): don't give them your 'best' work. I have worked and worked and worked on a piece, only to have it come back for rewrites that were impossible...it's like the CE had to find something, and since it was good, they found nit-picky things. I often send in pieces where I can 'see the errors' myself. Often they go through 'as is.' If they do come back for re-writes, it's the stuff I already saw, and it's easy to fix. For $15 an article, do not give them your best.