<p>As a counterpart to <a href="https://stackoverflow.com/questions/215470/c-coding-guideline-102">C++ Coding Guideline 102</a>, which of the <a href="http://www.gotw.ca/publications/c++cs.htm" rel="nofollow noreferrer">101 guidelines of Sutter &amp; Alexandrescu</a> do you violate or ignore most often, and why?</p>

I'd say for me, it's probably 16. Avoid macros. I find there are a good number of things I can only do with macros (especially inlining __FILE__ and __LINE__ into expressions), and many cases where I need a compact expression which operates in the external function context (checking result codes and returning, for example). As a result, my code tends to be sprinkled liberally with assertions in the form of macros, for example, so I'd say this is one I ignore quite a bit.
That said, I would forgo most of my uses if the language allowed alternative similarly compact expressions of the same concepts, but since it does not, macros will be around for a long time.
I should add, it's not to say that I think the suggestion is bad, or it's bad to follow it when you have an alternative available. I just find that I end up using a lot of macros, usually because there's no alternative available.