Both use keyword research to uncover popular search terms. The first step for both SEM and SEO is performing keyword research to identify the best keywords to target. The research includes looking at keyword popularity to determine the top keywords or buying keywords that your ideal audience searches for. It also includes looking at keyword competition to see what other brands are targeting the same keywords and determining what you will need to do to compete with those other companies.
Don’t be a website Google won’t rank – What Google classifies your site as – is perhaps the NUMBER 1 Google ranking factor not often talked about – whether it Google determines this algorithmically or eventually, manually. That is – whether it is a MERCHANT, an AFFILIATE, a RESOURCE or DOORWAY PAGE, SPAM, or VITAL to a particular search – what do you think Google thinks about your website? Is your website better than the ones in the top ten of Google now? Or just the same? Ask, why should Google bother ranking your website if it is just the same, rather than why it would not because it is just the same…. how can you make yours different. Better.
At first glance, the Ads or SC appear to be MC. Some users may interact with Ads or SC, believing that the Ads or SC is the MC.Ads appear to be SC (links) where the user would expect that clicking the link will take them to another page within the same website, but actually take them to a different website. Some users may feel surprised or confused when clicking SC or links that go to a page on a completely different website.
“Sharability” – Not every single piece of content on your site will be linked to and shared hundreds of times. But in the same way you want to be careful of not rolling out large quantities of pages that have thin content, you want to consider who would be likely to share and link to new pages you’re creating on your site before you roll them out. Having large quantities of pages that aren’t likely to be shared or linked to doesn’t position those pages to rank well in search results, and doesn’t help to create a good picture of your site as a whole for search engines, either.
Search engine optimization (SEO) is often about making small modifications to parts of your website. When viewed individually, these changes might seem like incremental improvements, but when combined with other optimizations, they could have a noticeable impact on your site's user experience and performance in organic search results. You're likely already familiar with many of the topics in this guide, because they're essential ingredients for any web page, but you may not be making the most out of them.
And so on and so on. The point of this step isn't to come up with your final list of keyword phrases. You just want to end up with a brain dump of phrases you think potential customers might use to search for content related to that particular topic bucket. We'll narrow the lists down later in the process so you don't have something too unwieldy. Once you have your final list, there are several data-driven tools available to you for finding out which keywords you're most likely to rank well for. 
Black hat SEO attempts to improve rankings in ways that are disapproved of by the search engines, or involve deception. One black hat technique uses hidden text, either as text colored similar to the background, in an invisible div, or positioned off screen. Another method gives a different page depending on whether the page is being requested by a human visitor or a search engine, a technique known as cloaking. Another category sometimes used is grey hat SEO. This is in between black hat and white hat approaches, where the methods employed avoid the site being penalized but do not act in producing the best content for users. Grey hat SEO is entirely focused on improving search engine rankings.
If you are improving user experience by focusing primarily on the quality of the MC of your pages and avoiding – even removing – old-school SEO techniques – those certainly are positive steps to getting more traffic from Google in 2019 – and the type of content performance Google rewards is in the end largely at least about a satisfying user experience.
SEM is a broader term than SEO, and is used to encompass different options available to use a search engine’s technology, including paid ads. SEM is often used to describe acts associated with researching, submitting and positioning a website within search engines.  It includes things such as search engine optimization, paid listings and other search-engine related services and functions that will increase exposure and traffic to your Web site. 
For me, when SEO is more important than branding, the company name goes at the end of the tag, and I use a variety of dividers to separate as no one way performs best. If you have a recognisable brand – then there is an argument for putting this at the front of titles – although Google often will change your title dynamically – sometimes putting your brand at the front of your snippet link title itself. I often leave out branding. There is no one size fits all approach as the strategy will depend on the type of page you are working with.

Ever heard of Maslow's hierarchy of needs? It's a theory of psychology that prioritizes the most fundamental human needs (like air, water, and physical safety) over more advanced needs (like esteem and social belonging). The theory is that you can't achieve the needs at the top without ensuring the more fundamental needs are met first. Love doesn't matter if you don't have food.

QUOTE: “The score is determined from quantities indicating user actions of seeking out and preferring particular sites and the resources found in particular sites. *****A site quality score for a particular site**** can be determined by computing a ratio of a numerator that represents user interest in the site as reflected in user queries directed to the site and a denominator that represents user interest in the resources found in the site as responses to queries of all kinds The site quality score for a site can be used as a signal to rank resources, or to rank search results that identify resources, that are found in one site relative to resources found in another site.” Navneet Panda, Google Patent

QUOTE: “So sites that don’t have much content “above-the-fold” can be affected by this change. If you click on a website and the part of the website you see first either doesn’t have a lot of visible content above-the-fold or dedicates a large fraction of the site’s initial screen real estate to ads, that’s not a very good user experience.” Google 2012

Try and get links within page text pointing to your site with relevant, or at least, natural looking, keywords in the text link – not, for instance, in blogrolls or site-wide links. Try to ensure the links are not obviously “machine generated” e.g. site-wide links on forums or directories. Get links from pages, that in turn, have a lot of links to them, and you will soon see benefits.
SEO is also about making your search engine result relevant to the user's search query so more people click the result when it is shown in search. In this process, snippets of text and meta data are optimized to ensure your snippet of information is appealing in the context of the search query to obtain a high CTR (click through rate) from search results.
Don’t break Google’s trust – if your friend betrays you, depending on what they’ve done, they’ve lost trust. Sometimes that trust has been lost altogether. If you do something Google doesn’t like such as manipulate it in a way it doesn’t want, you will lose trust, and in some cases, lose all trust (in some areas). For instance, your pages might be able to rank, but your links might not be trusted enough to vouch for another site. DON’T FALL OUT WITH GOOGLE OVER SOMETHING STUPID
The actual content of your page itself is, of course, very important. Different types of pages will have different “jobs” – your cornerstone content asset that you want lots of folks to link to needs to be very different than your support content that you want to make sure your users find and get an answer from quickly. That said, Google has been increasingly favoring certain types of content, and as you build out any of the pages on your site, there are a few things to keep in mind:

Search engines may penalize sites they discover using black or grey hat methods, either by reducing their rankings or eliminating their listings from their databases altogether. Such penalties can be applied either automatically by the search engines' algorithms, or by a manual site review. One example was the February 2006 Google removal of both BMW Germany and Ricoh Germany for use of deceptive practices.[54] Both companies, however, quickly apologized, fixed the offending pages, and were restored to Google's search engine results page.[55]
I think ranking in organic listings is a lot about trusted links making trusted pages rank, making trusted links making trusted pages rank ad nauseam for various keywords. Some pages can pass trust to another site; some pages cannot. Some links can. Some cannot. Some links are trusted enough to pass ranking signals to another page. Some are not. YOU NEED LINKS FROM TRUSTED PAGES IF YOU WANT TO RANK AND AVOID PENALTIES & FILTERS.
The length of a title tag that Google will show will vary (it’s based on pixels, not character counts) but in general 55-60 characters is a good rule of thumb here. If possible you want to work in your core keyword, and if you can do it in a natural and compelling way, add some related modifiers around that term as well. Keep in mind though: the title tag will frequently be what a searcher sees in search results for your page. It’s the “headline” in organic search results, so you also want to take how clickable your title tag is into account.
Structured data21 is code that you can add to your sites' pages to describe your content to search engines, so they can better understand what's on your pages. Search engines can use this understanding to display your content in useful (and eye-catching!) ways in search results. That, in turn, can help you attract just the right kind of customers for your business.