In Mandarin, the pitch of a syllable is part of the word. The same sounds with a different tone can be a different word, so tones matter from your first day.
Mandarin has four main tones. The classic example is the syllable ma:
mā 妈 “mother”
High and level. Hold one steady, high note, as if singing.
má 麻 “hemp”
Rises from the middle to high, like asking “what?” in English.
mǎ 马 “horse”
Low, dipping before it rises. In most speech it stays low and barely rises.
mà 骂 “to scold”
Falls sharply from high to low, like a firm “no!”.
Some syllables are short and light, with no tone of their own. Pinyin leaves them unmarked, as in māma (妈妈, mom) or the question word ma (吗). Their pitch depends on the syllable before them.
A mark sits above a vowel: ā first, á second, ǎ third, à fourth. The shape of the mark follows the movement of your voice. Some textbooks use numbers instead, such as ma1, ma2, ma3 and ma4.
1. Train your ear first: hear a syllable and name its tone until it feels easy.
2. Say single syllables and check your pitch, because it is hard to judge your own voice.
3. Move on to tone pairs. Real words combine tones, and pairs are where most mistakes happen.
4. Learn every new word with its tones from the start, not as an afterthought.