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)