One of my kids asked me the other evening what a 'rule of thumb' was, and why it's called that. I explained that when people say that, they really mean that someone's come up with a practical guideline that applies in most situations, and checked out the Wikipedia Rule of Thumb article for the origin of the term, which appears to be uncertain.

With the idea of rules of thumb in mind, I've pulled together a set of 'project management rules of thumb' from my own experience, and selected other sources. Please feel free to comment o­n any of the o­nes that I've identified, or suggest others for adding to the list. Keep these in mind along with other guidance specific to the type of engineering you are using, such as estimating rules of thumb for software engineering.

1. Warning: dates in the calendar are closer than you think.
2. There are few truly good project managers, but many more lucky o­nes; but the more you plan, the luckier you get.
3. Good project managers admit mistakes: that's why you so rarely meet a good project manager.
4. Good project managers know when not to manage a project.
5. The most successful project managers have perfected the skill of being comfortable with being uncomfortable.
6. The most valuable and least used word in a project manager's vocabulary is "NO".
7. The most valuable and least used phrase in a project manager's vocabulary is "I don't know".
8. There's never enough time to do it right first time but there's always enough time to go back and do it again. There just may not be enough budget, in which case there will be a new& project manager.
9. Most projects would not have been started if the truth had been told about the cost and schedule.
10. The more ridiculous the deadline, the more money will be wasted trying to meet it.
11. Nothing is impossible for the person who doesn't have to deliver.
12. Everyone asks for a strong project manager - when they get one, they usually change their mind about what they ask for.
13. The person who says it will take the longest and cost the most may be the o­nly o­ne with a clue about how to do the job.
14. You may con a sucker into committing to an impossible deadline, but you cannot con him into meeting it.
15. The conditions attached to a promise are forgotten, o­nly the promise is remembered.
16. The bitterness of poor quality will last long after the sweetness of making a date is forgotten.
17. There is such a thing as an unrealistic timescale.
18. If you don't know where you're going, any road will take you there.
19. If you fail to plan, you are planning to fail.
20. Projects have two patterns: a) Planned and then executed or b) Executed, stopped, planned and then executed.
21. There is o­nly nice thing about not planning: failure comes as a complete surprise rather than being preceded by a period of worry and depression.
22. In the absence of an up-to-date plan, nothing really gets done till nothing gets done (i.e. until everything falls apart, and good planning is re-established).
23. Planning without action is futile; action without planning is fatal.
24. At the heart of every large project is a small project trying to get out.
25. The same work under the same conditions will likely be estimated differently by ten different estimators or by o­ne estimator at ten different times. Without an understanding of their assumptions, they may appear to all be wrong, but may in fact may all be right!
26. Any project can be estimated accurately o­nce it's completed. Prior to that, the confidence levels of the estimates should always be factored into your thinking.
27. Feather and down are padding - changes and contingencies will be real events.
28. A two year project may take three years, but a three year project will never finish.
29. A project gets a year late o­ne day at a time.
30. Directions which are not captured in written words might as well not have been given. Even if it's written down, if it's not understood and acted o­n, it doesn't matter.
31. Overtime is a figment of the naïve project manager's imagination as a means of planned capacity.
32. It's not the hours that count; it's what you do in those hours.
33. Good control reveals a problem early - which means you'll have longer to worry about them.
34. If project content is allowed to change freely, the rate of change will exceed the rate of progress.
35. If you can interpret project status data in several different ways, o­nly the most painful interpretation will be correct.
36. What you don't know will likely hurt you.
37. Fast - cheap - good: getting any 2 is easy, getting all 3 requires divine intervention.
38. Without discipline, anything that can be changed will be changed, until there is no time left to change anything.
39. If you don't attack the risks, the risks will attack you. A little risk management up front saves a lot of fan cleaning later.
40. If you don't stand for something, you'll fall for anything.
41. If it looks like a duck, walks like a duck and quacks like a duck, don't expect it to soar like an eagle.
42. Too few people o­n a project are unable to solve all the problems that present themselves - too many create more problems than they solve. The key is to prioritize problems by estimates of risk and exposure, and track whether you are falling ahead or behind the curve in abating those risks.
43. Of several possible interpretations of a particular written or oral communication, the least convenient o­ne is likely to be the correct o­ne.
44. In programming, the sooner you begin coding, the later you finish.
45. The sooner you get behind on your schedule, the more time you have to make it up.
46. A verbal contract isn't worth the paper it's written o­n.
47. Work expands to fill the time available for its completion (Parkinson's law); If something can go wrong it will (Murphy's law); and it will go wrong in the worst possible way (Sod's law).
48. Murphy, Sod and Parkinson are alive and well - and working o­n your project, and all of them are optimists.
49. If everything appears to be going exactly to plan, something somewhere is going massively wrong.
50. If there were no problem people, there would be no need for people who solve problems.
51. Without discipline, anything that can be changed will be changed, until there is no time left to change anything.
52. There is no such thing as scope creep, o­nly scope gallop.
53. When all is said and done, a lot more is usually said than done.
54. If it were not for the 'last minute', nothing would get done.
55. If there is anything to do, do it! However, never confuse activity for achievement.