Developing better sentence structure and sentence formation skills in English grammar for CBSE Class 9 is essential for effective communication. Here are some tips to help you improve your skills in this area:

1. Understand the Basic Sentence Structure:
- A sentence should have a subject (the doer of the action) and a predicate (the action or state of being).
- The subject and predicate should agree in terms of number and person.

2. Expand Your Vocabulary:
- Learn new words and their meanings to enhance your sentence formation.
- Use a thesaurus to find synonyms and antonyms for words you commonly use.
- Practice using new vocabulary in context to ensure proper usage.

3. Use Correct Punctuation:
- Understand the purpose and correct usage of punctuation marks such as commas, periods, question marks, exclamation marks, etc.
- Use punctuation marks appropriately to indicate pauses, questions, emphasis, etc.

4. Use Different Sentence Types:
- Vary your sentence structure by using different types such as declarative, interrogative, imperative, and exclamatory sentences.
- This will make your writing more interesting and engaging.

5. Pay Attention to Sentence Length:
- Avoid using overly long sentences that may confuse the reader.
- Break complex ideas into shorter sentences for better clarity and understanding.

6. Organize Your Thoughts:
- Before writing, create an outline or plan to organize your ideas.
- This will help you structure your sentences more effectively.

7. Proofread and Edit:
- After writing, proofread your work to identify and correct any errors in sentence structure, grammar, and punctuation.
- Make necessary revisions to improve sentence formation and overall coherence.

In conclusion, developing better sentence structure and formation skills in English grammar for CBSE Class 9 requires a combination of understanding the basic rules, expanding vocabulary, using correct punctuation, utilizing different sentence types, paying attention to sentence length, organizing thoughts, and proofreading/editing. Regular practice and seeking feedback from teachers or peers can also greatly aid in improving these skills.