7 ingredients for a relatively smooth Ph.D

Why do most Ph.D's take longer than "expected"?
Why is the end often extremely stressful for students?

On the one hand there can be a multitude of reasons. However, I would contend that often some basic things are overlooked or neglected, leading to problems.

Some people have come up with things like "7 secrets of highly successful research students". These title is good marketing but not accurate of the content. The ideas are not "secret" and they don't lead to "high success," just "moderate" success [i.e. completion in a reasonable amount of time] and reduced stress.

The reworked version below is due to Rob Hyndman, a Professor of Computer Science at Monash University, on his nice blog Hyndsight

1. Meet reg­u­larly with your supervisor.
2. Write up your research ideas as you go.
3. Have real­is­tic research goals.
4. Beware of dis­trac­tions and other commitments.
5. Set reg­u­lar hours and take holidays.
6. Make full use of the avail­able help.
7. Per­se­vere.

Some of this may be "obvious" and "basic". But actually doing all seven consistently requires significant discipline. I think most students struggle (as I did) because they neglect at least one of these.

I first encountered these "7 keys" in a nice presentation from the UQ graduate school. They run a whole range of "candidature skills training" workshops for postgraduate students. The presentation slides are online, but appear to be only available to the UQ community.
These are good examples of the "available help" students need to "make full use of".