Had better 意為「最好」、「應該」，後接原形動詞，與語氣助動詞 should 的用法相似，其中的 had 在口語和非正式寫作中經常縮略為 ‘d 或完全省略。例如：
- You had better go before it rains. (你最好在下雨前就去)
= You’d better go before it rains.
= You better go before it rains. - I’d better be making tracks. (我該走了/我要走了)
= I’d better get going.
= I’d better be off in a (little) bit.
然而，在正式或學術文章中，一般並不建議使用 had better 或 better，而應使用 should 或 ought to。例如：
- You should go to school today. (你今天應該上學)
- You ought to go to school today.
在上面的例句中，should 和 ought to 的意思相同，都是表示建議、勸告的「應該」。另外，順便一提的是，ought to 在口語中經常寫成 “oughta” 或發 “otta” 的音，就像 have to 經常發成 “hafta” (has to 發 “hasta”) 的音一樣。
雖然 had better 與 should (或 ought to) 都是表示勸告或建議，但 had better 只能對特定的情況而不能對普遍的情況提出勸告或建議，若要對普遍的情況提出勸告或建議，則須使用 should。例如：
- You should brush your teeth before you go to bed. (睡覺前你應該刷牙)
- He should dress more appropriately for the office. (上班時他的穿著應該要更得體)
不過，should 亦可針對特定的情況提出勸告或建議。例如：
- You shouldn’t say anything. (你什麼都不該說)
- He should get back to work. (他應該回去工作)
- We should meet early. (我們應該早點見面)
然而，had better 針對特定情況所提出的勸告或建議，帶有警告或威脅會有不良後果的意味。例如：
- You’d better do what I say or else you will get into trouble. (你最好按照我的話去做，否則你就會有麻煩)
- I’d better get back to work or else my boss will be angry with me. (我最好回去工作，否則我老闆就要生氣了)
- We’d better get to the airport by five or else we may miss the flight. (我們最好在五點之前到達機場，否則我們可能會搭不上飛機)
值得注意的是，had better 中的 had 不能用 have 或 has 來替換；再者，”had” 雖是過去式，但從上面的例句可知，had better 是表示一種現在或未來的情況。不過，had better 可用 had best 來代替，但 had best 的使用頻率比 had better 來得低。例如：
- You had best get home before midnight. (你最好在午夜之前回到家裡)
- We’d best get going. (我們最好現在就走/我們該走了)
Had better 的否定形式是將否定副詞 not 放在 had better 的後面，不是放在 had 的後面。例如：
- You’d better not disturb him. (你最好別去打擾他)
- You had better not miss the last bus. (你最好別錯過末班公車) (正)
You had not better miss the last bus. (誤)
Had better 通常不以一般疑問句的形式出現，若要使用這種疑問形式，則將 had (不是 had better) 置於主詞之前，如 What had we better do? (我們該怎麼辦呢?)。Had better 用於否定疑問句的情況比較多，常用「Hadn’t + 主詞 + better …?」結構，這是一種勸告形式，比肯定句的語氣來得委婉。例如：
- Hadn’t you better take an umbrella? (你是不是該帶一把傘呢?)
- Hadn’t you better ask him first? (你是不是該先問問他呢?)
- Hadn’t we better go now? (我們是不是現在就去呢?)
至於 had better 的附加問句如下列所示：
- You’d better not go out today, had you? (你今天最好不要外出，好嗎?)
- You had better go for a doctor, hadn’t you? (你最好去看醫生，不是嗎?)
Had better 後接動詞進行式 (had better + be + V-ing)，係表示最好馬上做某事；若接完成式動詞 (had better + have + P.P.)，則表示本該做某事但並未去做。例如：
- I think I’d better be/get going. (我想我該走了)
- We’d better be getting our clothes ready. (我們最好馬上把衣服準備好)
- We had better be watching TV. (我們最好馬上就看電視)
- We had better be starting back now. (我們最好現在就動身回去)
- You had better have done it. (你本來應該把那件事做好的) － 但實際上卻沒做。
- You had better have stayed with us. (你本來應該跟我們待在一起的) － 但實際上卻沒有。
Had better 亦可用於祈使句，此時 had 往往省略。例如：
- Better not do it. (最好別做那事)
- Better not wait for him. (最好不要等他了)
- Better say yes, if your wife asks you. (如果你太太問你，你最好說「是」)