Memorizing the Hiragana/Dakuten

Dakuten ( ﾞ ) and Handakuten ( ﾟ ) are marks placed after certain hiragana that modify the way the consonant is pronounced. These marks indicate that the consonant of the syllable should be voiced.

Exceptions
"Shi" (し) turns into "Ji" (じ)

"Chi" (ち) also turns into "Ji" (ぢ)

"Tsu" (つ) turns into "Zu" (づ)

Iteration marks
Iteration marks ( ゝ) indicate that a sound is to be repeated. Iteration marks can also be combined with dakuten.

Sokuon
Sokuon (っ) is a symbol consisting of a small Tsu (compare with normal Tsu: つ). It is used to insert a slight pause.

For example: うた = song うった = hard

The Sokuon gives a pause to make a meaningful sound.

Chōonpu
Chōonpu (ー) is a symbol used to indicate a long vowel sound. Long vowels can also be written by using the corresponding vowel hiragana.