Here are the top 10 factors that positively affect your search engine rankings

Keyword Use in Title Tag
Anchor Text of Inbound Links
Global Link Popularity of Site
Age of Site
Link Popularity within the Site's Internal Link Structure
Topical Relevance of Inbound Links to Site
Link Popularity of Site in Topical Community
Keyword Use in Body Text
Global Link Popularity of Linking Site
Topical Relationship of Linking Page

1. Keyword Use in Title Tag

In Laymen's Terms: Include the search keywords you are targeting in your webpage's title tag.

If you have time to do only one SEO action on your site, take the time to create good titles. - Christine Churchill

The title tag (or "meta title") is the text that appears at the top of your browser window. Think of it as the title for the webpage. The meta title is also what is displayed as a link in search results.

In the HTML code, the meta title is the text between the <title> tags. For example, the meta title of this article looks like this in the HTML code:

<title>Improve Search Engine Rankings - Tips to Improve Search Engine Rankings</title>

Your Action: Use the search keywords you're targeting in every webpage's title tag. Have a customized title for each page; don't be lazy and use the same title for every page on your site.

For WordPress users, you can install the All-in-One SEO Pack plugin. It lets you modify the title tag of each blog posts.

2. Anchor Text of Inbound Links

In Laymen's Terms: When other sites link to your webpages, how do they describe the link?

Anchor text of the inbound link is one of the most concise assessments another person can make about what your site/page is 'about'.

Choose anchor text that helps your website/page rank better for your targeted keywords. For example, if I were to ask for a link to this article, I would ask for anchor text that says something like "Search Engine Ranking Factors". That anchor text tells search engines that the link goes to a page about "search engine ranking" -- the search keywords that I would love to have this article rank prominently.

That anchor text is better than "the most awesome article ever written". While it would be interesting to see which anchor text generates more clicks from human surfers, there is no doubt that the keyword-rich version of the anchor text would help this article's ranking in search results much more than the keyword-less version.

3. Global Link Popularity of Site

In Laymen's Terms: How many other websites are linking to your site?

I am a strong believer that a sites overall link popularity drastically effect rankings.- Neil Patel

In general, the more inbound links to your website, the better it is for you. Every inbound link is a "vote" for your site. If lots of other websites link to you, search engines conclude that lots of people find your content useful or interesting. That makes your webpage rank higher than a similar page with fewer inbound links.
Make link building -- the practice of getting more inbound links to your site -- a central part of your online marketing strategy.

4. Age of Site

In Laymen's Terms: The older your website, the better. I believe it's always had some importance and within the past two years, aging has taken on more signifigance in the ranking factors.
- Scottie Claiborne

Older sites have more weight than newer sites. The age of a website is hard to fake. Plus, search engines figure that if your site has been around for so long, it's probably better than a brand new site.

5. Link Popularity within the Site's Internal Link Structure

In Laymen's Terms: How prominent is the webpage within your own site?

Without the proper linking structure, certain pages may not get enough emphasis. For example, ... links directly from the homepage usually do really well. - Neil Patel

The more prominently you feature a particular page on your site, the more weight search engines will give it.

Your Action: Showcase your best content or the webpage you most want to highlight. Put it in your main navigation menu or link to it from your homepage.

6. Link Popularity of Site in Topical Community

In Laymen's Terms: How popular is the site that is linking to you? Especially withing your niche.

A niche site may not have a high quantity of links but a few links from the 'authorities' in the neighbourhood is often enough to rank the site above the authorities for niche-related keywords. The authoritative sites are telling the search engines "Hey, we're voting for this site for these niche (anchor text) keywords".

7. Global Link Popularity of Linking Site

In Laymen's Terms: Links from big websites (ie., sites that have lots of inbound links) are worth more than links from smaller sites.

I like links that are linked to by many sites. I think there's a big difference between a PR 6 site with 20,000 links and a PR 6 with 500 inbounds.- Roger Montti aka martinibuster

8. Topical Relationship of Linking Page

In Laymen's Terms: Relevance matters. Links from a webpage that is related to your page's content are worth more than links from random, unrelated sites.

Focus your link building efforts on sites within your niche(anchor text).