1. set site url with or without wwww

Settings>General Setting>Chosse Wordpress Adress URL

2. disable user registration

setting>membership>anyone can register

3. setup time zone, date format &time format

setting>general setting>save local time zone, date format and time format

4. update wordpress ping list

Setting>Writing>Update Service

5. default discussion settings

setting>discussion>default article setting
setting>discussion>other comment setting

6. default avatar

7. change image location from media

setting>media>uploading files 
//uncheck organize my uploads into mont-and-year based folders option

8. change default permaling settings

setting>permalinks
<code>

9. change or delete default admin user
<code>
user>all user 

10. acivate akismet 11. setup gogle analytics 12. verify your blog in webmaster tools and submit sitemap

Source and further (13-20) steps