Five months into 2015, and search and content marketers have likely been deep into the grind of links, keywords, content, and conversions.

As you keep working hard (and smart), you would do well to adopt the following five strategies to keep your momentum going into the next year.

1. Send social signals

A lot of digital marketers complain about the low proportion of incoming traffic from social platforms in relation to the efforts spent on those platform, but a silver lining has finally been added to the social big picture.

Just as backlinks act as votes for your site, raising your domain authority and rankings, so too does the popularity of content you share on social media.

After years of hemming and hawing about social media's relative importance to search rankings, Google finally acknowledged its place as a valuable visibility factor, albeit in a subtle way.

Late in 2014, Google loosened its grip and took the first steps toward allowing non-Google social media platforms to be featured on its search engine results pages (SERPs). Social media platforms other than Google+ made their entry into Google's Knowledge Graph.

With the removal of Google authorship, as well, from search result snippets, you can expect social signals from popular platforms to gain in importance in the years ahead.

2. Befriend mobile

In the past few years, many have predicted the coming of age of the mobile Web. With the share of smartphones at 77% of the US mobile market, those predictions are finally coming true. Further, mobile Internet activity now stands at over 30% of all Internet traffic and half that of desktops.

Recognizing these landmark changes in browsing patterns, Google took the bold step of tagging sites on its SERPs as "mobile-friendly" as a tip off to searchers. Obviously, the click rates and engagement for sites tagged specifically as mobile friendly would be higher than others'.

So, for starters, hurry up and switch to responsive design, if you haven't already. Heed the site markers that Google uses to confer this tag on websites and implement these changes on your site ASAP, including the following:

• Having buttons that are large enough to be clicked easily on a small mobile device
  
• Ample whitespace to prevent the "fat finger syndrome"
  
• Copy that is large enough to read without zooming in
  
• Links that are placed fairly apart to avoid wrong navigation

Take Google's Mobile-Friendly Test and make sure your site passes with flying colors.

3. Migrate to HTTPS

With the recent spate of large-scale data breaches, including the infamous Heartbleed bug, security has been a centerpiece of most digital conversations. Gone are the days just e-commerce retailers, financial websites, and the like having to spend time and energy building airtight websites with SSL encryption.

In a move toward a safer browsing experience for all users, in August 2014 Google announced it would be using HTTPS as a definite ranking signal.

HTTPS (HTTP Secure) is a technology for transferring data between your site and the Web server with an additional layer of encryption called SSL (Secure Socket Layer) to make data transfer extra secure.

Keeping the ever-worsening Web security situation in mind, combined with Google's announcement regarding HTTPS as a ranking signal, it is definitely worth your while to invest in an SSL certificate for your site. It's even more important if your site needs login authentication or handles sensitive user data.

(However, bear in mind that SEO-related things can go wrong when migrating your HTTP site to HTTPS.)

4. Don't abuse guest blogging

As content gained acceptance as the route to earning links and growing authority, there was a mad rush in 2012 and 2013 toward guest-blogging simply for the sake of a link, no matter how irrelevant or unimportant the referring site. Thousands of low-quality websites and blogs mushroomed, soliciting guest posts and offering backlinks in return.

Not surprisingly, that proliferation of guest posting sites did not go unnoticed, and in early 2014 Google's Matt Cutts specifically highlighted guest-blogging as a strongly undesirable method of earning SEO points.

In the words of Google's whip-cracker himself: "If you're using guest blogging as a way to gain links in 2014, you should probably stop."

But that does not mean you need to close the doors on guest blogging in 2015; it just means that resorting to spammy guest posts on spammy sites is a terrible, terrible idea.

To avoid incurring Google's wrath, resolve to put quality over quantity. Aim to acquire extremely high-quality links from respected and well-read websites rather than simply anyone who agrees to publish your content.

Doing so is easier said than done, however. A guest post on a high-quality site comes with two requisites:

• Creating undeniably great content
  
• Building a lasting relationship with high quality sites in your niche as opposed to simply looking for one-off links from them

5. Focus on contextual search

Semantic search shot into focus with Hummingbird in 2013. SEOs of all kinds rushed to optimize their content to not just keywords but also their synonyms, product- and brand-related phrases, different content formats, and so on.

In 2014, the semantic processing capabilities of Google bots got more refined. A smart SEO strategy would approach keyword research from the perspective of search intent. So, now, you must think like a user and come up with as many combinations as possible for queries related to your product or brand.

Instead of using single keywords to build authority, consider conversational queries that use natural language structures. If you do have to focus on keywords, use universal transactional words like sale, buy, cheap, discount, etc. to build probable search queries for your products or brands.

"Content that links back to your site does not have to be in your face with exact or partial match, or even branded keywords as your anchor text," says Vaibhav Kakkar, co-founder of RankWatch, which offers backlink and on-site SEO analysis in addition to monitoring rankings.

He concludes from analysis on its links-to-rankings correlation data that even a mere citation with no link back to your page adds to your ranking potential, as long as your brand is mentioned in a relevant context.

Even if your products are alluded to along with those of your competitors, search engines pick up on the fact that your brand belongs to the same product category as the others. If any of the brands that share space with yours happen to have high online authority, some of that authority rubs off on you via association.

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Google continues to keep SEO practitioners on their toes. The good news is that SEO is now more about how useful your site is to the end user than how adept you are at gaming Google's ranking systems.

The challenge? It's an uphill task to be truly useful to today's well-informed and savvy searcher.