I am very much an open-door policy person, but people abuse my open door and just drop in and it throws my time management out, so now, I have a period every day in the morning where I close the door and get on with things I need to do in an uninterrupted way.
Email is not the first thing I do. I do my email after I have had my own undisturbed work time and have achieved the things I have to get done.
I use my calendar slavishly. If I have an appointment, a task to be completed, it goes in my calendar. I also use an electronic to do list and keep a notebook next to me in which I make many lists of things I need to get done. I don’t rely on my memory.
When I check email and there is something I need to respond to but can’t do it straight away, I often print off that email and keep it with my paper to do list. Otherwise, things get buried in my email box.
I also have weekly meetings with people I am working on projects with. Those meetings don’t need to be in person though. Phone is fine to touch base and is more efficient from a time perspective than a physical meeting. I also get one person to make notes of what is decided and to email it to all participants with clear information about who was nominated to do what when.
I agree with @CWOTUS. Rather than people just presenting problems, I encourage them to also suggest solutions. I do this with my own boss.
Delegate where you can. Look at what you are doing, the meetings you are attending. Can someone else do those more menial tasks? Do you have to have a physical meeting or can you meet over the phone or something like Skype? Spend a little time each week looking at what took up most of your time and whether there was another way you could have managed that time.
Factor in some time to go for a walk, spend time with your family, have a coffee with a friend. We all need to do these things and in the end, I think those little breaks make us more productive. Sometimes, my meeting with my friends might be as simple as “I will meet you here and we will walk up to the car park tonight together”. Not ideal, but it means I can touch base with people I care about. Put things like this in your calendar. Don’t leave it to .. if I get time.