Now that ISBN number is received and bar code is generated. The next step is to check with your designer nd placed it on your book cover. Well, now is the time to prepare the book to be sent to printing press.
Make sure the book interior is ready. Yes, now onwards your manuscript would be called book interior. Most printers do not do any settings on the interior unless you have taken typesetting services from them. Once your coverpage and interior is good to go, start searching for a printer. You can take help from marketplace websites such as Indiamart and negotiate with them. You need to choose your paper carefully based on the type of book. The details that they would need would include:
1.Cover page paper type
2.Interior paper type
3.Matte or Gloss finish on Cover page
4.Flip side printing or not on Cover page
5.Full text interior or graphics also included
6.Type of binding (hardbound or perfect bound). Perfect bound is preferred for paperback.
7.Number of copies you want to print. This is a strategic question as the more the number of copies the less cost per copy for your readers to purchase your book. Offset printing minimizes the cost only if the copies are in thousands. If you do not want to take the market risk or are on tight budget go for digital printing but atleast print 50-100 copies to create some wave. And lastly negotiate.

One key thing is always ask your printer to give you one proof copy for review so that you know if your cover design or interior would have any issues. This proof copy is complimentary and they print your cover page on a flat sheet and print interior pages that you choose and loosely staple them to make it look like a book so that you can see page numbering and all. I would suggest take a couple of days to review this copy and then give them go ahead as this is your last chance for revision. And finally sit and home and plan a book launch as your books get printed.