The constructions like “it is OK to do…”, “it is OK if you…” using 良い is extremely common in Japanese. They are usually translated in English as “you can/may/should…”, and especially in conversation used almost exclusively over other constructions like “～すべきだ”, “～することが出来る”.

• 宿題が終わったら遊んでも良い -> You can play when you finish your homework
• ニンニクが無ければチャイブを使っても良い -> It’s OK to, you can, use chive if there’s no garlic
• 嫌ならやらなくても良い -> You don’t have to do it if you don’t want to
• 好きなだけ食べて良い -> You can eat as much as you want
• 勝手にすれば良い -> You can do whatever you want. Suit yourself
• もう少し待ったほうが良い -> It’s better to, we should, wait a little longer
• 固くて混ぜにくい時は少し温めると良い -> When it is too thick and hard to mix, warm it up a little and it gets easier
• 緊張している時は深呼吸すると良い -> Taking deep breaths works well when you are nervous
• どうすれば良いのか分からない -> I don’t know what I should do

The opposite of 良い is usually NOT 悪い, but rather 良くない, いけない, 駄目だ, 不味い, etc..

• 塗装が乾くまで触ってはいけない -> Don’t touch until the paint dries
• 一日四錠以上服用してはいけない -> Don’t take more than four pills in a day
• そんなに簡単に諦めてはいけない -> You shouldn’t give up so easily
• 慌てて結論を出すのは良くない -> You shouldn’t make a rush decision
• ただ待っているだけでは駄目だ -> Just waiting is not good, won’t solve anything. You have to act
• 弱気になっては駄目だ -> You cannot be pessimistic, passive
• 上司の許可無しでやるのは不味い -> It is not good, it will be a problem, if we do this without the boss’s authorization

“しないほうが良い”, “止めたほうが良い” are also very common.

• 慌てて結論を出さないほうが良い -> You shouldn’t make a rush decision
• 彼に期待するのは止めたほうが良い -> You should not raise your hope on him
• 風邪をひいている時は無理をしないほうが良い -> It is better not to exert yourself when you have a cold