1. Explain it simply
Use 不 (bù) to negate things that are generally true now or in the future, like habits, plans, or states.
Use 没 (méi) to say something did not happen or does not exist, especially with 有 (yǒu).
2. Show examples
我不去商店。
Wǒ bù qù shāngdiàn.
Sandhi:Wǒ bú qù shāngdiàn.
I am not going to the store.
Habit or plan → use 不
他不喝茶。
Tā bù hē chá.
He does not drink tea.
Daily preference → use 不
我们没有狗。
Wǒmen méiyǒu gǒu.
We do not have a dog.
No possession → use 没有
3. Share a tip
If the verb is 有 (to have), always negate with 没有, never 不有. For other verbs, use 不 unless you are talking about the past.