You can throw out the action plans, productivity apps and Pomodoro timers. Just do this one thing for a dramatic increase in productivity.
First, a little back story...
In 2004, I was a fledgling web designer. I was working full time in a different industry, studying part-time for my MCSD certificate. (Yep. That's a Microsoft qualification. GASP). I'd built a few sites for friends and colleagues and landed some paying jobs and business was picking up.
I started building sites with an open source CMS called Mambo. Out went the Microsoft books in favour of Teach Yourself PHP in 24 Hours and Teach Yourself MySQL in 21 days.
Within 12 months, Joomla forked from Mambo and suddenly open source was considered mainstream. Enquiries were coming in. I started picking up work from agencies. I quit my day job and focused on web development full-time. This new career was awesome.
The problem
Around 2009 things started to change. I now had a portfolio of clients that needed updates. New projects were getting bigger and harder to quote. The phone wouldn't stop ringing, emails were coming in... all... day... long.
I was working days and nights and falling behind. In fact, I was so busy I couldn't get anything done.
At the end of a particularly busy day in 2009 I checked my phone log. 2 hours and 19 minutes were spent on the phone that day.
I'd also received and responded to 54 business related emails. I calculated a total of 5 hours fielding calls and emails. There's also the time lost by not being in the "zone" - especially as a coder.
The solution
That night I wrote a post on my blog announcing my intentions.
In the spirit of productivity and better service I was making myself less available.
In order to get things done, I would check emails twice a day and phone messages once a day. When I'm working, the phone and email are turned off. If anybody wants me they will have to leave a message. From that day on, I easily doubled the amount of actual work I was getting done in a day.
The fallout
You know what? There wasn't any negative fallout. It turns out people don't mind waiting for a few hours.
This is still how I work today. It usually takes about an hour to answer emails in the mornings. If anything requires my attention that isn't critical, it gets scheduled for the next day. From 9:00am to about 4:00pm is dedicated to what ever tasks I have planned. No interruptions.
When clients know you're working and the phone is off, they are more inclined to use email. It's better for everyone.
Give it a go. You won't regret it.