Another good idea is to cut out every scheduled appointment that you possibly can. You'll be amazed the difference this makes. People love to put things on your calendar: things like "lunch a week from Tuesday." But for anyone in the occupation of creating things, it's hell to end up in a calendared life that's completely interrupt driven. What if you end up in the middle of some really good work on Tuesday? Why is it your flow that gets broken and not your appointments, no matter the priorities? My advice is to challenge these appointments; make them fight for survival.
For the lunch example, I tell people that I'd love to do it, so please text me the morning of and I'll let you know if I can make it. That answer is (1) more realistic, and (2) more flexible.
You can do this for meetings, too. Rather than immediately setting up a "2pm brainstorming session," tell them that you'll email over your thoughts and ideas sometime tomorrow.
I really don't understand how scheduling fixed-time appointments became the natural order. Challenge that assumption and you'll be amazed at how it impacts life for the better.