choosing type of capacitor
Since you said this is for audio, the answer is actually more tricky than you probably imagined.  Electrically, you want a non-polarized capacitor, which means not electrolytic or tantalum in practise.

However, various types of capacitors have other tradeoffs that matter in audio applications.  Multi-layer ceramics are nice in that they have good capacitance for the size and are not polarized.  However, depending on the dielectric material, they can be quite non-linear and have another effect often called microphonics.

Microphonics is because the material exhibits a bit of the piezo effect.  Vibrations will cause small voltage changes, which means the capacitor will act as a microphone.  The effect is more subtle than piezo microphones deliberately designed for that purpose, but it can still be significant given the high signal to noise ratio of good audio.

The non-linearity is also a function of the dielectric material.  A perfect capacitor will increase its voltage the same amount when a fixed charge is added no matter what the other conditions are.  These non-linear dielectrics will have a different change in voltage for the same change of charge depending on the voltage.  This is usually quantified as capacitance varying as a function of voltage.  For example, a "10 &micro;F 10 V" capacitor may act like 10 &micro;F in the &plusmn;2 V region, but act more like a 5 &micro;F capacitor to incremental change in the 8-10 V region.  This non-linear response in audio circuits can cause harmonics that were not present in the original signal, which means distortion is added.

Ceramic dielectric types that start with "X" or "Y" in their name exhibit both these effects more than ceramic like "NP0".  In a lot of applications, either effect doesn't matter, and the X and Y ceramics are useful because they give you more capacitance per volume.  For audio applications it does matter, so you stick to the other types and realize that you won't be able to use the capacitors with the seemingly great capacitance and voltage combinations in the signal path.  Heavily derating the voltage range also helps against dielectric non-linearity.  For example, you might get a 20 V cap when the circuit guarantees the voltage accross it will always be within &plusmn;3 V.

Other dielectrics like mylar, polystyrene, and the like have less undesirable effect in the audio signal path, but also will have much lower capacitcances available and will be physically more bulky and probably more expensive.

Everything is a tradeoff.