昨 zuó previous
Made up of [日 rì sun; day radical 72, 乍 zhà at first; suddenly; abruptly ]Made with 9 strokes.
The 'sun' on the left suggests 'yesterday; previous' the second part used to give rpough phonetic
Ancient small seal form 
Related characters
Also uses 日 rì component: 白 bái (bright) 曾 céng (once) ; 昌 chāng (prosperous) ; 春 chūn (spring) ; 旦 dàn (dawn) ; 婚 hūn (to marry) ; 间 jiàn (gap) ; 间 jiān (between) ; 景 jǐng (bright) ; 旧 jiù (old) ; 明 míng (bright) ; 莫 mò (do not) ; 普 pǔ (general) ; 晴 qíng (clear sky) ; 是 shì (is) ; 时 shí (time) ; 暑 shǔ (heat) ; 晚 wǎn (evening) ; 香 xiāng (fragrant) ; 星 xīng (star) ; 阳 yáng (yang) ; 易 yì (easy) ; 音 yīn (sound) ; 影 yǐng (picture) ; 早 zǎo (early) ; 照 zhào (according to) ; 者 zhě (in process of) ; 桌 zhuō (table) ; 最 zuì (most)
Also uses 乍 zhà component: 怎 dìng (how) 窄 xué (narrow) ; 炸 zhà (to explode) ; 作 zuò (to do)