This is how the world felt before Crackberries. (LeoLuigi)

“Not-to-do” lists are often more effective than to-do lists for upgrading performance.

The reason is simple: what you don’t do determines what you can do.

Here are nine stressful and common habits that entrepreneurs and office workers should strive to eliminate. The bullets are followed by more detailed descriptions. Focus on one or two at a time, just as you would with high-priority to-do items. I’ve worded them in no-to-do action form:

1. Do not answer calls from unrecognized phone numbers

Feel free to surprise others, but don’t be surprised. It just results in unwanted interruption and poor negotiating position. Let it go to voicemail, and consider using a service like GrandCentral (you can listen to people leaving voicemail) or Simulscribe (receive voicemails as e-mail).

2. Do not e-mail first thing in the morning or last thing at night

The former scrambles your priorities and plans for the day, and the latter just gives you insomnia. E-mail can wait until 10am, after you’ve completed at least one of your critical to-do items…

3. Do not agree to meetings or calls with no clear agenda or end time

If the desired outcome is defined clearly with a stated objective and agenda listing topics/questions to cover, no meeting or call should last more than 30 minutes. Request them in advance so you “can best prepare and make good use of the time together.”

4. Do not let people ramble

Forget “how’s it going?” when someone calls you. Stick with “what’s up?” or “I’m in the middle of getting something out, but what’s going on?” A big part of GTD is GTP — Getting To the Point.

5. Do not check e-mail constantly — “batch” and check at set times only

I belabor this point enough. Get off the cocaine pellet dispenser and focus on execution of your top to-do’s instead of responding to manufactured emergencies. Set up a strategic autoresponder and check twice or thrice daily.

6. Do not over-communicate with low-profit, high-maintenance customers

There is no sure path to success, but the surest path to failure is trying to please everyone. Do an 80/20 analysis of your customer base in two ways–which 20% are producing 80%+ of my profit, and which 20% are consuming 80%+ of my time? Then put the loudest and least productive on autopilot by citing a change in company policies. Send them an e-mail with new rules as bullet points: number of permissible phone calls, e-mail response time, minimum orders, etc. Offer to point them to another provider if they can’t conform to the new policies.

7. Do not work more to fix overwhelm — prioritize

If you don’t prioritize, everything seems urgent and important. If you define the single most important task for each day, almost nothing seems urgent or important. Oftentimes, it’s just a matter of letting little bad things happen (return a phone call late and apologize, pay a small late fee, lose an unreasonable customer, etc.) to get the big important things done. The answer to overwhelm is not spinning more plates — or doing more — it’s defining the few things that can really fundamentally change your business and life.

8. Do not carry a cellphone or Crackberry 24/7

Take at least one day off of digital leashes per week. Turn them off or, better still, leave them in the garage or in the car. I do this on at least Saturday, and I recommend you leave the phone at home if you go out for dinner. So what if you return a phone call an hour later or the next morning? As one reader put it to a miffed co-worker who worked 24/7 and expected the same: “I’m not the president of the US. No one should need me at 8pm at night. OK, you didn’t get a hold of me. But what bad happened?” The answer? Nothing.

9. Do not expect work to fill a void that non-work relationships and activities should

Work is not all of life. Your co-workers shouldn’t be your only friends. Schedule life and defend it just as you would an important business meeting. Never tell yourself “I’ll just get it done this weekend.” Review Parkinson’s Law in The 4-Hour Workweek and force yourself to cram within tight hours so your per-hour productivity doesn’t fall through the floor. Focus, get the critical few done, and get out. E-mailing all weekend is no way to spend the little time you have on this planet.

It’s hip to focus on getting things done, but it’s only possible once we remove the constant static and distraction. If you have trouble deciding what to do, just focus on not doing. Different means, same end.

What other no-no’s would you add to the list?

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