The w, z, ei, ie and ch Sounds, Plus the Umlauts ä, ö and ü
German uses the same Latin alphabet as English and Indonesian, which is exactly where the trouble begins: the tongue reads familiar letters with old habits. In German, w sounds like an English v (Wasser is said vasser), v often sounds like f (Vater is said fater), z sounds like ts (Zeit is said tsite), and j sounds like an English y. The pair ei is always said like eye, while ie is a long ee, so Wein (wine) and Wien (Vienna) sound clearly different.
There are two ch sounds. After a, o, u and au it is a rough sound at the back of the throat, as in Buch. After e, i and consonants it softens into a light hiss against the palate, as in ich and Milch. At the start of a word, sp and st become shp and sht (sprechen, Straße), and at the end of a word b, d and g lose their voicing, so Hund sounds like hunt.
The dots over a vowel change meaning: schon means already, while schön means beautiful. The sound ä is close to the e in bed. For ö, learners say a long e and round their lips without moving the tongue; for ü, they say a long ee with the same rounded lips. The letter ß is a sharp s that follows long vowels (Straße, groß), and after short vowels the same sound is spelled ss (Wasser).
Practice works best with lists of word pairs that differ by a single sound, read aloud in front of a mirror and recorded on a phone, then compared with native-speaker audio. Any sound that drifts gets marked for another round the next day.
The skill has settled when learners can read an unfamiliar German word aloud and a listener can tell schon from schön by sound alone.