Second Inversion Chords?

Hello everyone! I read somewhere that second inversions must be treated with care because of their dissonance. So my question is how/when do you use them, and what are the "rules" for preparing them?

IN TRADITIONA PART-WRITING, second inversion chords in triads (7th chords are different) are almost always used for one of very few reasons: as a pedal point, as a passing motion, or as a cadential figure. The reason it is dissonant as a triad is because your bass voice will always have the richest overtones, rising up in an extended major chord. When the distance between the bass and two upper voices is a fourth and a sixth (a 6/4 chord, or a 2nd inversion chord aka), the overtones of the bass note conflict with the sounding voices above. That's where your dissonance comes from.

If you don't write traditional music, I'd say don't worry about it too much. It's good to learn traditional part-writing, don't get me wrong. But practically speaking, write what you want.

Oh I see, thanks guys!

Because the 2nd inversion is so unstable, it should be used sparingly. Speaking of traditional harmony of course.