MOZ has an excellent guide about how to get started with SEO, the link to it is this:
There are two types of SEO that you need to know:
On-Page SEO: 20% Important
- Optimize the title with the keywords you want to cover.
Repeat you keyword on the text from 1% to 5% of the overall text.
Include images with the keyword in the alt atribute.
Include links to external websites.
Include links to your internal pages.
Write sentences of no more than one and a half line and paragraphs of no more than four lines.
Optimize your metadescription.
(The last two are for User Experience, that's very important to decrease your bounce rate).
Off-Page SEO: 80% Important
- Links from other websites pointing to the specific page you want to rank up on Google results.
The activity of your page on Social Media.
There's a lot more factors that influence SEO but those are the most important. Getting backlinks is the toughest part of SEO, but there are plenty of guides over the Internet.
To make easy all the "getting-backlinks" work, your website needs to bring something of true value to people. On the other hand, if your site sucks, it will be a headeache to get backlinks.
Google has this tool named "Google Keyword Planner". It's a free tool where you can search for keywords related for an specific term (ex. "Web designer in Austin"). That tool lets you check the average monthly searches a keyword has. It's an awesome tool, and it's FREE, you just have to sign up.
Hope this help you!