Guest blogging is a two-way street. In addition to posting content to other blogs, invite people in your niche to blog on your own site. They’re likely to share and link to their guest article, which could bring new readers to your site. Just be sure that you only post high-quality, original content without spammy links, because Google is cracking way down on low-quality guest blogging.
Hey Ted, thanks for the great questions! The peak times refer to your particular time zone, if you are targeting an audience that resides in the same zone as you. You can also use tools to find out when most of your audience is online. For example, Facebook has this built into their Page Insights. For Twitter, you can use Many social posting tools also offer this functionality.
If you havent see it already, check out the links in shor's comment below - there are some great resources in there. In some cases you can also consider surveying your current audience or customers through email, on-site surveys or SurveyMonkey.  Be sure to ask for some profiling information that you can use for determining specific persona needs like age, sex, location, etc. (Probably best not to make it sound like a creepy text chat like I just did though...)  :)

Black hat SEO involves techniques such as paying to post links to a website on link farms, stuffing the metadata with nonrelated keywords, and using text that is invisible to readers to attract search engines. These and many other black hat SEO tactics may boost traffic, but search engines frown on the use of such measures. Search engines may punish sites that employ these methods by reducing their page rank or delisting them from search results.
My company has been working on a large link building project. We’ve already performed extensive keyword research and link analysis and now we’re considering executing an email outreach campaign. However, all the content we’ve created up until this point is geared more towards our target audience as opposed to the key influencers of our target audience. Do you think it would be worth it to try to build backlinks to our existing content or are we better off creating new content that directly appeals to the influencers of our target audience?

It’s free to be active in online groups and on websites that are relevant to your business and community—and it helps you to obtain more traffic. Comment on blogs and social media posts, answer questions people are posting, and participate in conversations about your industry. The more you engage with your community, the more exposure and profile visits you get.
In 1998, two graduate students at Stanford University, Larry Page and Sergey Brin, developed "Backrub", a search engine that relied on a mathematical algorithm to rate the prominence of web pages. The number calculated by the algorithm, PageRank, is a function of the quantity and strength of inbound links.[22] PageRank estimates the likelihood that a given page will be reached by a web user who randomly surfs the web, and follows links from one page to another. In effect, this means that some links are stronger than others, as a higher PageRank page is more likely to be reached by the random web surfer.

Search engines use complex mathematical algorithms to interpret which websites a user seeks. In this diagram, if each bubble represents a website, programs sometimes called spiders examine which sites link to which other sites, with arrows representing these links. Websites getting more inbound links, or stronger links, are presumed to be more important and what the user is searching for. In this example, since website B is the recipient of numerous inbound links, it ranks more highly in a web search. And the links "carry through", such that website C, even though it only has one inbound link, has an inbound link from a highly popular site (B) while site E does not. Note: Percentages are rounded.