If possible, and it isn’t always, try to write in your optimal time. In my case, that’s first thing in the morning. Luckily, I can shift my hours around and start work around 9 or 10 on most days. I plan on doing that. I also can get up at 5 in the morning and skip a long soak in the bathtub, so on days where I can’t start work late, I can still get at least a little writing done first thing.
Also, despite my thinking that I can’t write late at night (which I define as after 8 p.m.), if there’s a jabber word war, I find myself suddenly able to write.
A sandwich at my desk (or in a quiet conference room) can give me forty-five minutes to write during the middle of the day.
I bring notebook and paper (if not laptop) everywhere, and if waiting in line, can jot down notes. I find that by constantly writing, I get a lot done even on days where I don’t have a large block to dedicate to writing.
I also find that if I “bring a character with me” like to the grocery store, while I’m not actually writing while shopping for groceries, I can picture him or her interacting which makes it easier to write when I do sit down in front of the computer. I once “brought a char along” on a road trip to DC, and enjoyed the drive since I kept imagining what the char would say about everything–even road signs!