If you want to get penalized by Google take following steps: 1. Cheap spam links - buy 5,000 back-links for £ 5.00 2. Link Exchange with other sites 3. Hiding links in web codes 4. Excessive links for websites like purchasing or submission 1000 directories or social bookmarking links in 7 days or 15 days etc. 5. Links from other languages i.e. your site in English and you are posting links on Spanish, Chinese or on French language sites. 6. Duplicate contents and website codes Last but not the least, for long run business and success keep away from these and similar things on world wide web.