1. How's everything going? I'm eager to hear from you.

2. It was a pleasure to receive your correspondence. I've been looking forward to catching up.

3. You raised a question about (topic/issue), and I've given it considerable thought. Here's what I think.

4. Time flies; it feels like ages since we last met. I hope this letter finds you well.

Endings:

1. I eagerly await your response.

2. Thank you in advance for your letter.

3. Please do write back at your earliest convenience.

4. Wishing you all the best.

Additional Tips for English Letter Writing:

- Always capitalize the first letter of a closing salutation and end with a period.

- Tailor your closing to the relationship with the recipient: "Sincerely Yours," for a close friend; "Your Loving Son (Daughter)" for parents; "Respectfully Yours" for elders; "Faithfully Yours" for business.

- Sign your name in ink below the closing, and do not add punctuation after your signature.

How to Address an Envelope in English:

1. Write the sender's name and address in the upper left corner of the envelope.

2. Center or place the recipient's name and address in the middle or slightly lower left corner of the envelope.

3. Use the honorific Mr., Mrs., or Miss before the recipient's name.

4. List the address from smallest to largest unit: apartment number, street, city, state (and province, if applicable), postal code, and then the country.

5. Affix a stamp to the upper right corner of the envelope.

References: English Letter Writing - Wikipedia, the free encyclopedia.