Dear, you will find different tactics for SEO as you can say black hat technique and white hat tachnique and Grey hat technique..but we have to do only white hat technique which is ethical way to promote the website for long term prospective and also aware from Google Algorithms from time to time...
There are basically two types of SEO, i onpage seo ii offpage seo In offpage seo there are some of the techniques such as social bookmarking, directory submission, article submission,blog creation and many more..
All have different views and they are correct in their own mean. But most of professional companies who ask they can bring top results in less time like 1 or 2 months, they often use Black Hat SEO, means automated software submissions. But this is risky, if we get fast ranking by making a trick to search engine, then some times search engine may spam our keyword. So the white hat SEO is always better, no chance to spam but it gradually increases the ranking of website. However it takes much more time depending on hours spent to build the backlinks and traffic. At last I think an individual is better than any company. As of work load company make use of software but an individual do not.
One more thing it is better to start a PPC campaign rather than wasting the money to doing Black Hat SEO which is risky for our website..
I know only Two Types of SEO. 1) White Hat SEO 2) Black Hat SEO. White Hat SEO is Good Technique For Search Engine.