Because the act of linking to a site does not imply ownership or endorsement, you do not need to ask permission to link to a site that is publicly accessible. For example, if you found a site's URL through a search engine, then linking to it shouldn't have legal ramifications. There have been one or two cases in the U.S. that implied that the act of linking without permission is legally actionable, but these have been overturned every time.
In United States jurisprudence, there is a distinction between the mere act of linking to someone else's website, and linking to content that is illegal (e.g., gambling illegal in the US) or infringing (e.g., illegal MP3 copies). Several courts have found that merely linking to someone else's website, even if by bypassing commercial advertising, is not copyright or trademark infringement, regardless of how much someone else might object. Linking to illegal or infringing content can be sufficiently problematic to give rise to legal liability.Compare  For a summary of the current status of US copyright law as to hyperlinking, see the discussion regarding the Arriba Soft and Perfect 10 cases.
Keep in mind that the number of average monthly searches for each suggested keyword is an estimate. However, it does represent the popularity of that keyword or search term. This makes a difference when doing your keyword research, as it gives you insight into what people in your market are searching for. Understanding what they want allows you to better position your business to provide them with relevant content and information.
Keep in mind, this will often mean shifting the focus of your business from more general to more specific products or services. For instance, instead of exclusively offering general home renovation services, you could consider specializing in "one day bathroom renos" or "custom kitchen makeovers." These more specific keyword phrases will likely be much easier to rank for, which will mean you can start ranking that much faster.
Basically, what I’m talking about here is finding websites that have mentioned your brand name but they haven’t actually linked to you. For example, someone may have mentioned my name in an article they wrote (“Matthew Barby did this…”) but they didn’t link to matthewbarby.com. By checking for websites like this you can find quick opportunities to get them to add a link.
To do this, I often align the launch of my content with a couple of guest posts on relevant websites to drive a load of relevant traffic to it, as well as some relevant links. This has a knock-on effect toward the organic amplification of the content and means that you at least have something to show for the content (in terms of ROI) if it doesn't do as well as you expect organically.
The first step that I take is to do a quick Google search to find pages on my domain where I've mentioned the keyword in question so that I can add an internal link. To do this, I'll use the following search query, replacing DOMAIN with your domain name (e.g. matthewbarby.com) and KEYWORD with the keyword you're targeting (e.g. "social media strategy"):
After you hit “Get ideas,” you will see the number of average monthly searches for the term you entered, plus other related search terms that you may want to use as keywords on your website. Create a list of the keywords and search terms you want to rank for, and fold them in to your website copy and content as naturally as possible. As Google sees your website using these keywords, it will view your site as a relevant and quality search result.