Buying books online - some how tos, tips and thoughts

• Ask in quora.com for the best books in your topic of interest
• Read the reviews about those books in amazon.com. Make sure that the rating is good, if not great. Beware of those reviews which are done by the author's buddies. Check the date of publication and the date of review to get some idea ( usually fake reviews are added immediately after publication date, and they are added in the same week or month)
• Even if a book's rating is good, read the contents and the first chapter on amazon. Make sure it captivates you. The best book still may not work for you, so watchout.
• Search for the price of the book in atleast 4 e-commerce sites. In India, I search at flipkart.com, indiaplaza.com, homeshop18.com, bookadda.com, and sapnaonline.com. Don't buy immediately. Impuse is maya. Just put the book on wishlist. Give atleast 1 week, sleep over the book, and decide if you really need the book. There are also sites like mysmartprice.com and junglee.com which do price comparisons. 
• If you really need the book, order the book based on what is priority for you - cost, delivery time,quality of service, etc.