1. Here is a checklist and some tips.

2. Here are a checklist and some tips.

(Are both grammatical?)

3. Get help from friends. If you ask them, they will help you. You can buy a study book. It will help you too.

4. You need to get help from your friends. They will help you with your subjects. Or you can buy study books. They will make you get better grades.

5. If you want to receive better grades, you should know how to study. From your friends you can get help. They will let you know how to study. Go to a bookstore, and you can find many kinds of good study books. Buy books you need, and if you study with the books, you can get better grades later. Keep up your good work!

(Would you check the passages from #3 to #5? If there are any errors, correct them, please.)

#1 is grammatically corect I think it sounds better.

In #4 They will make you get better grades. The correct way to say that is They will help you get better grades.
In #5 From your friends you can get help. The correct way to say that is You can get help from your friends.

# 1 is not correct. The subjects are "a checklist and some tips." Therefore, you need a plural verb.

Here ARE a checklist and some tips.

1. Both sentences are grammatical. The only difference is the placement of "here." In sentence 1, "here" comes before "is," while in sentence 2, "here" comes after "are."

3. The passage is grammatically correct.

4. Here is a revised version: "You need to seek help from your friends. They will assist you with your subjects. Alternatively, you can consider purchasing study books. They will help you improve your grades."

5. Here is a revised version: "If you want to achieve better grades, it is important to know how to study effectively. Seek assistance from your friends; they will guide you on effective study techniques. Additionally, make a visit to a bookstore where you can find a wide variety of high-quality study books. Purchase the books that cater to your needs and study with them, as this will contribute to better grades in the future. Keep up the good work!"