✨ ベストアンサー ✨
The grammar is very good, well done.
✖🟠🟠 Also, we had better buy only what you really want and carry your own bag to...
Don't change the subject from "we" to "you", it breaks the logic.
🟠🟠 Also, we had better buy only what we really want and carry our own bag...
want --> need
🟠 Also, we had better buy only what we really need and carry our own bag to...
carry --> take (~持っていく) or bring (~持ってくる)
✅ Also, we had better buy only what we really need and take our own bag to the shop to reduce the amount of garbage.
"Had better" is correct but sounds very formal and a bit commanding (like a parent to his child).
✅ Also, we should only buy what we really need and bring our own bag to the shop to reduce the amount of garbage.
🟠 These lead to saving electricity and to decreasing CO2 emissions.
✅ These measures/actions lead to saving electricity and to decreasing CO2 emissions.
✅ Such actions can contribute to saving ...
🟠 We have many chances to defend global warming in daily life.
✖ to defend <bad thing>
✅ We have many chances to fight against global warming in daily life.
✅ We have many chances to defend the world against global warming in daily life.
✅ We have many opportunities to fight against global warming in daily life.
✅ be careful with spelling (gloval, decresing)
I hope this is helpful. Keep up the good work!
細かいところまでありがとうございました！