Sounds

There are 23 initials and 35 finals in Mandarin romanization (there are five more finals, but they share the same symbols as other finals).  These combine to form about 420 different sounds.  A word consists of  (initial) + final + tone.  In some cases, the initial can be omitted.

To hear a particular initial or final, you can use the Mandarin Sound Chart.

Initials

b, p, m, f, d, t, n, l, z, c, s, zh, ch, sh, r, j, q, x, g, k, h, y, w.

The initials "z" and "j" are very similar and can be easily confused.  The "z" is pronounced somewhat clipped and sounds very much like the "j" sound.

The initials followed by an "h" (zh, ch, and sh) add an "r" sound to the end of finals "i" and "e"

"C" is pronounce close to "ts" as in "church" but with less emphasis.

The initial "X" is pronounced softly, sometimes resembling an "sh" sound.

"Q" is pronounced as a "ch" sound.