If you want to buy a book on some particular topic and want to find out the best books in that topic, internet can be very helpful in finding out the right book for you.

Try these steps for searching books:

amazon.com (The best place to do research on books)

1. Go to http://books.amazon.com
2. Click on the Advanced Search link on the top left of the screen
3. Enter your search criteria.
4. There is a drop-down called Sort Results by. By default it is set to ‘Relevance‘. I generally use ‘Bestselling‘ (to know about the most popular books) and ‘Avg. Customer Review‘ (to know about the best rated books).
5. Click on the ‘Search Now‘ button.
6. You get a search results listing various books. Click on any of the book which you are interested in.
7. The detail of the book is displayed. You get lot of information here. Go down, you’ll find ‘Editorial Review‘. I think this is the best part of this page because this is a review which is not done by the publisher. It is very difficult to get such reviews on a book when you visit a book store to buy a book. Go down even further, you can find lot of customer reviews and know how much rating the customers are giving to this book. I find this to be very useful.

books.google.com (good place to read sample pages of books)

1. Go to http://books.google.com/ 
2. Enter search criteria which is typically the book name and/or author’s name. Click on the Search button.
3. You get search results listing various books.
4. Click on the link pointing to the book which you want.
5. You reach the detail page for the book. Note, google might ask you to log-in if you are not already logged-in to google.
6. Here you can have a look at the book’s Front Cover, Copyright, Table of Contents, Index, Back Cover and sample pages (for some books). You can see it exactly as it appears on the book! 
7. Going through these pages will help you get information like topics covered in the book (Table of Contents & Index), latest edition of the book available & sometimes you can even read the sample pages to get an idea of narration style, language used in the book etc.

Note: As of now http://books.google.com/ coverage of books is not so extensive. You might not be able to find the book you are looking for in the search result. I believe that over a period of time google will cover more (or most) books. 

An explanation of a book search done by me using these methods:

Problem definition: I wanted to buy a good book which can teach me the basics of photography.

How I went solving my problem:

1. A friend of mine who is a professional photographer suggested me to buy a book by John Hedgecoe. He didn’t suggest me any particular title.
2. I went to advanced search of amazon.com. Here I entered ‘John Hedgecoe‘ in the Author column and set the Sort Result by drop-down to ‘Bestselling‘. Now I clicked on Search Now button.
3. I came to know best selling books of John Hedgecoe are ‘The Book of Photography‘ and ‘The New Manual of Photography‘ are the most popular books of John Hedgecoe.
4. I did more research on the books by Hedgecoe by going through the reviews of the books to find out the right book for myself. The New Manual of Photography and John Hedgecoe’s Complete Guide to Photography, Revised and Updated looked to be the kind of books that I need. 
5. I visited http://books.google.com/  and entered ‘John Hedgecoe’ in the search box and clicked on Search button. The search result didn’t have all the books which I was looking for. It only had …Complete Guide… amongst the books I was interested in. I went to the details of this book and had a look at the ‘Index‘ page. By seeing this I realized that this book has got a good coverage on Digital Photography also (I am looking to purchase a digital SLR). So, I felt that this is probably the right book for me to purchase.

Note: This is a good way to do research on books. I use this technique to short list right books for myself and I visit local book store and have a look at the book before I purchase it. I generally purchase books from Book World in Gandhibazaar (cos’ they give good discounts, around 20% for computer books & also the shopkeepers have good knowledge of books)  & Gangaram’s or Sapna for other books not available in Book World.

PS: I should also consider visiting Mahesh’s Corner book stall in Garuda Mall cos’ Mahesh is a good friend of mine