5) Social Media Links
Social media is a double-edged sword. Links re-tweeted and re-posted on various social media sites are getting increased attention from search engines because the people working on the search engines understand that those links represent entities which are currently popular. On the other hand, the people working on search and spam detection understand that social media is filled with spam, and marketing agencies specializing in "gaming" social media sites by advanced and creative spamming/advertising techniques. Ultimately, social media is becoming more of a factor in search rankings, and because there is lots of spam in social media, the search engines likely give a higher fault tolerance to suspicious activities because if they didn't, they would have to penalize a very large number of people, and they can't realistically do that. Just be careful not to push your luck.
6) SEO is Spam and Ruins the Web
Search Engine Optimizers do employ a number of techniques that may be seen by some as spam. They tend to get their sites linked to from just about anywhere they can get away with. Such practices have given SEO's a bad name over the years. But SEO's also make the web better. They create many links that unify the web and bring related content closer together, making it easier to surf, and increasing the chances of people finding what they are looking for. In many ways, while SEO's are often responsible for spam or bad search result findings, probably much more frequently when we do surf to something interesting or find what we want via search, it is the work of SEO's to help us find the content and we should appreciate it.
7) Paying for Directories
Paying for directories has been losing popularity over the years, and in May 2010, Google changed their algorithm in a way that dropped many sites which were ranking high largely due to techniques like paying for directory placement. That made paying for directories even less attractive that it was already becoming. Even if people pay to be placed in link directories, few people understand what value they are getting when they buy a placement in a directory.
Here is the breakdown of how sites should approach paying for directories. The best paid directory is the Yahoo directory and after that, the quality drop is quite steep. If you are a big and established site, likely not even a Yahoo directory listing will help you in any noticeable way because you are already at quite a peek. If your site is small or young, and needs that extra little boost, perhaps the Yahoo directory listing will provide just the boost you may need. If you have an appetite to pay for more directory listings, try to aim for vertical directories which focus on theme of your site. But paying for directories other than Yahoo is generally not recommended.
8) Reciprocal Linking
This once popular method has become nearly extinct because search engine companies try to destroy and discourage link-exchange schemes, but this approach still works extremely well. In fact, if a site links to other sites, but none of them link back, search engines see that as a little bit of an unusual occurrence and a bit of a red flag. It only makes sense that a site would link to other sites with similar content, and those sites would link back. So don't refrain from linking back if it makes sense to do that. As a rule of thumb, when something makes local sense to do, don't worry too much about search engines.
9) You Know Who Links to You
No matter how many tools a person can use to check which sites link to their sites, every tool shows different results. Some data always overlaps, some just doesn't get found by different tools. Each back link finding crawler has different crawl algorithms and find different sites in different parts of the web. In order to have a more precise approximation for who is linking to you, try to use more than one tool to check who links to you. But in the end, some links will get lost and might not be indexed, or ever shown to you in a tool you use.
10) It Takes 6 months to Do an SEO Campaign
This is a common saying and in many ways it is true. First you have to create the content, then the search engines have to crawl and index that content, and then you have to build links from different part of the web to that content. Then it takes time to do analysis on the success of the campaign. So yes, if you took this approach it might take a number of months. But in a business environment, 6 months can be a lifetime. The truth is that Google has become so good and fast at ranking and re-ranking sites, and then distinguishing good links from useless ones, that it can take as little as 3-4 days to determine whether something you tried will work or not. In my experience, one of my sites got a Wikipedia link (very trusted by search engines) and 3 days later, I saw that site jump from the 6th page to the 4th page for a very difficult 1-term keyword I was targeting.