Seth Godin has some radical (especially in the Indian context), but very useful, advice for authors. Of the 19 points he lists, here are a select few
2. The best time to start promoting your book is three years before it comes out. Three years to build a reputation, build a permission asset, build a blog, build a following, build credibility and build the connections you'll need later.
11. Blurbs are overrated, imho.
12. Blog mentions, on the other hand, matter a lot.
All authors, both aspiring and published, would do well to read Seth Godin's entire list.