Optimize Headings:

Headings are used all over a Web site. You'll use them to differentiate different sections. Headings are another very important place to put your keywords.

Headings are of six types. h1 to h6. Use headings according to what font size you need. If you use h1 as your heading and the font size is too big. Customize the font size in CSS.

Text and how to optimize the text:

engines are crawling your Web site. They value bold text more than simple text. It's a good place to put your keyword but in a fair way do not go on your website and bold all of your keywords. 

Google will penalize you for that and your visitors will hate it. You should bold one or two keywords on a page. Bold text can be really helpful if used correctly.

optimize the Images:

Search engines are getting very smart but they're still not as smart in recognizing pictures. Many search engines are working on that but they're still not as smart.

We have to tell the search engines that this is an image of "phone" and then search engines will store it as an image of "phone".

 alt tags:  Image alt tag is used for that purpose to give a name for image so that search engines recognize that image.

<img src="mobile.jpg" alt="imgee-description">