1. Plan ahead There's nothing more terrible than frantically trying to pull something together an hour before class. I've been there and it's not a happy place for your mental health. I always try to stay 2-3 weeks ahead for my lesson planning.
2. Things don't work You know it always happens: Monday morning at 8am before the semester starts, there's a line-up of 5 people trying to use the photocopier to copy their syllabi and of course it breaks. Be organized and hit it a few days before, just in case.
3. Simple is best You don't need to reinvent the wheel and simple is almost always better. Of course, put a bit of effort and creative energy into your lessons, but it really is okay to use a page or two out of the textbook, or to use something like ESL Logic Puzzles and Trivia for your class warm-up instead of making your own, which would take hours.
4. Recycle Similar to not reinventing the wheel, hopefully you've been saving your lessons somewhere in a place like Dropbox or Google Documents. There are always plenty of generic "conversation" classes here in Korea where you are free to use anything you want and it's much easier to reuse an old lesson than to pull something new out of your hat.
5. Work space Make sure that you have a happy place where you can get work done so you can put some focused effort into stuff. For me, it's usually not at home and if I want to be productive, it's far better for me to go into my office, which I'm lucky enough to share with only 2 people who are rarely (if ever) there.
But for others, they share an office with 10+ people and of course, serious work is impossible in that kind of environment so those people could maybe find a quiet coffee shop near their house, a public library or set-up a space at home to do work.