SEO is not something you did anything and got result. It helps in branding and getting business. It seems you are very new and looking for cheap links, probably you have heard about earning links, I good link is equal to thousands of cheap links and also there is no fear of link spam.
Cheap links: Link Spam you may be victim of Penguin
Content Duplication leads Panda
Any activity you do knowingly or unknowingly which violets the guidelines of Search Engine can lead to removal from search engines, SEO is not something which is governed by some laws, rather here are guidelines which are closely associated with user experience and fulfilling the purpose of a website at maximum level. It also deals with trust and believe with any site it is why branding plays important role.
Most of experts I am sure have a strong experienced that what they are doing have less value than how they are doing
So once you have decided must check for above mentioned.