In my (humble) opinion, this can be best done through VFS Global instead of directly submitting in Indian Embassy. Advantage would be that VFS would verify all your documents and checklist before they go ahead and submit your documents to the Indian Embassy on your behalf. Once the passport is renewed, they will collect it and courier it to you as well instead of you having to go in person to collect it

1. What is required?

• Your original passports
• Passport photographs in required format – you can either take the photo in standard places like Walgreens / Walmart / Costco etc. and they will print it and give the photographs (comparitively these are a little expensive)

Link to get started

You would need to fill up the forms in the above site and generate a final tracking number (after paying through credit card for their services including passport renewal fee). If you are close to one of the VFS offices mentioned on their site, you can submit the documents in person. If not, you can mail the documents to the VFS office

2. Notarizing documents in USA
In case you need to notarize your documents, you would need to take them in person to any Chase Bank, Bank of America, UPS, USPS etc. along with your original passport for verification. Usually notary services in these places are free.

3. How long does it take for the renewal process?
Typically, after VFS receives the documents, it takes not more than 10 days for you to receive the extended passport.

4. When should I renew my passport?
You can not renew the passport more than one year before the expiration date of your current passport. Typically, many renew their passports when it has 6 months left on it