I really hate to see it when people spend a lot of money on SEO. Not that I blame them - every business owner would love to be high up in search engine listings for what they do. Too often, businesses throw much of their marketing budgets to agencies who go through a bloated and ineffective search engine optimization process. Sadly, this budget could have been used for more effective things, like improving the content and functionality of the actual site they want people to visit.
I will state this plainly: some SEO firms are merely selling snake oil. They capitalize on their clients not being knowledgeable on the subject of SEO and make it out to be larger and more complex than it actually is. Complicate it however you want, but in simple terms, SEO is merely the "street cred" of your site on the web.
Most agencies are honest and do mean well, but SEO services often amount to blindly throwing darts and hoping they hit a target. On average, Google changes its search algorithm more than once a day, and nobody will admit that they don't know with certainty what they're doing.
I don't want you to waste your money, and if you do go with a firm that offers SEO services, including me, you should be armed with some key facts.
Here is a very simple version of how search engines work: they read every page of your site* and determine how to catalog your site based on its content. For example, if you run a news site about video games, you will be cataloged as a video games news site. Your individual pages will also be cataloged too. In general, if your content is well written, you've already done the most important thing in SEO.
Most SEO experts will keep harping on things called "meta" content, especially "keywords". This is merely an invisible list of words in the code of a page. With our example of an article about Super Mario World, a list might be something like "Mario, Nintendo, Super Mario World, 16-bit". If you see them doing this (and they will) - stop them. Google and Bing don't care anymore. At one point in time, before search engines were smart, this keywords list would tell search engines how to catalog a page. These days, search engines are smart and only care about what is actually on your page, not what you insist it's about.
You can make the biggest, best, and most comprehensive site about video games on the web, but if actual people don't know it's there and aren't talking about you, it's almost as if you are invisible. Today, search engines track how many people mention you and link to your page, whether it be on other sites or popular social media sites like Facebook and Twitter.
This is the primary reason why SEO firms will want to make you a presence on every social media site you possibly can. Making profiles and accounts alone doesn't do a thing, however - you need to get people actually talking about you. This is why I will emphasize again that good content is the most important thing about SEO. You can't make people care about something that isn't worth caring about.
Some SEO firms will try to game the system. Be wary of SEO agencies that suggest:
Agencies may suggest releasing articles about you to PR and news wire sites. As long as you are persistent in doing this, it can help. One news blast to these entities won't do much good over the long haul, though.
There are certain variables that we cannot control: competition, a user's location, and a user's history. These variables greatly impact search engine listings.
Those are the basic things you need to know about SEO, and as you can tell, you can probably do most of it yourself with the help of your web developer.
Have some horror stories with SEO firms or even success? Hit up the comments below.