The official name of Chinese phonetic system is Pinyin which means "spelled sound" in Chinese. The Pinyin system transcribe Chinese characters into Latin script with 25 letters(the letter "V" is not used). It was developed in the 1950s and published by the Chinese government in 1958. The system was adopted as the official standard in Taiwan in 2009, where it is generally referred to as the New Phonetic System.

In this system, the correspondence between the letter and the sound is sometimes idiosyncratic, though not necessarily more so than the way the Latin script is employed in other languages. For example, the aspiration distinction between b, d, g and p, t, k is similar to that of English, but not to that of French. Z and c also have that distinction, pronounced as [ts] and [tsʰ],similar to the german z and to and the italian z of "pazzo", however these languages do not have the distinction. In the x, j, q series, the Pinyin use of x is similar to its use in Portuguese, Galician, Catalan, Basque and Maltese; and the Pinyin q is akin to its value in Albanian; both Pinyin and Albanian pronunciations may sound similar to the ch to the untrained ear. Pinyin vowels are pronounced in a similar way to vowels in Romance languages. 

The pronunciation and spelling of Chinese words are generally given in terms of initials and finals, which represent the segmental phonemic portion of the language, rather than letter by letter. Initials are initial consonants, while finals are all possible combinations of medials (semivowels coming before the vowel), the nucleus vowel, and coda (final vowel or consonant).

18 Initials:

b p m f
d t n l
j q x  
z c s  
zh ch sh r

35 Finals:

6 basic finals: a, o, e, i, u, ü
13 compound finals 
ai, ao, ei, ia, iao, ie, iou, ou, ua, uai, üe, uei, uo
16 nasal finals: an, en, ian, in, uan, üan, uen, ün
  ang, eng, iang, ing, iong, ong, uang, ueng

The pinyin system also uses diacritics to mark the four tones of Mandarin. The diacritic is placed over the letter that represents the syllable nucleus. Let's see four tones in Chinese:

Four tones:

Tone    Tone Mark  Number added to end of syllable
in place of tone mark
Example using
tone mark
Example using
First  ¯ 1 ma1
Second / 2 ma2
Third ˇ 3 ma3
Fourth \ 4 ma4
Netrual   5 or 0 ma ma5 or ma0

Chinese tones are really important while speaking. Different tones means different words. For example:

mā (妈) : mother <===> mǎ (马): horse

And also we have huge different words which are the same pronunciation, but different characters. For example:

shā : 杀( to kill), 沙( sand ), 刹(to break), etc

It seems very difficult if a student only learns Chinese characters one by one. An easier way to learn Chinese characters is to  learn words which usually consist of 2 or 3 characters. For example, "diàn" has different meanings with different characters. But if we say "diànhuà", here is only one mearning: telephone. So learning Chinese by words instead of characters is better. If you have any questions, feel free to leave me a message. I will reply as soon as possible.