User-agent: *
Disallow: /*?
Disallow: /index.php/
Disallow: /catalog/product_compare/
Disallow: /catalog/category/view/
Disallow: /catalog/product/view/
Disallow: /wishlist/
Disallow: /admin/
Disallow: /catalogsearch/ Disallow: /checkout/
Disallow: /onestepcheckout/
Disallow: /customer/
Disallow: /review/product/
Disallow: /sendfriend/
Disallow: /enable-cookies/
Disallow: /LICENSE.txt
Disallow: /LICENSE.html
Disallow: /skin/
Disallow: /js/
Disallow: /directory/
Lets consider each groups of commands separately.
Stop crawling user account and checkout pages by search engine robot:
Disallow: /checkout/
Disallow: /onestepcheckout/
Disallow: /customer/
Disallow: /customer/account/
Disallow: /customer/account/login/

Blocking native catalog and search pages:
Disallow: /catalogsearch/
Disallow: /catalog/product_compare/
Disallow: /catalog/category/view/
Disallow: /catalog/product/view/

Sometimes Webmasters block pages with filters..
Disallow: /*?dir*
Disallow: /*?dir=desc
Disallow: /*?dir=asc
Disallow: /*?limit=all
Disallow: /*?mode*
More reasonable to use canonical tag on these pages.
Blocking CMS directories.
Disallow: /app/
Disallow: /bin/
Disallow: /dev/
Disallow: /lib/
Disallow: /phpserver/