There are at least 20 important points need to be optimized in building a site for better Search Engine Optimization. Those are classified in 4 main factors, design and user experience, website structure and architecture, page optimization and promotion:
Design & User Experience
1. Choosing Themes/ Templates, make sure your templates are compatible with common browser like Google Chrome, Mozilla Firefox, Opera, Internet Explorer etc.
2. Mobile Ready Give your users seamless experience of your website. Mobile Technology are now growing, be ready when user move from PC to mobile phones, tablets, etc.
3. Use clean design and fast loading template. Minimize the size of Image / CSS/ JS and use good caching mechanisms.
Website Structure & Architecture
4. Use suitable website platform, If you're blogging then choose wordpress or blogger or other blogging platform you master. For ecommerce, forum, etc. choose the best and ensure fulfil your specific goals and needs.
5. Sitemaps, sitemap is a must, always create and submit xml sitemap to search engine.
6. Trash useless stuff, never use flash (shockwave), applets and non SEO friendly stuff unless you really need it.
On Page Optimization
7. Unique content, try to create your original content, never copycat.
8. Use specific title, strong and specific page title is the most important element to rank in search engine. Title is important to catch the searchers' attention, use it wisely for human and search engine robots.
9. Keywords density and high quality article, remember this is most of the most important thing. A good quality article / post must contains a decent keyword density related to title.
10. Tag Heading, use tag heading like H1, H2, H3 to highlight the post head, sub title, and other important thing on your post.
11. Permalink and SEO Friendly URL, use targeted keywords included in the URL. This will emphasize title and content.
12. Use breads crumbs and rich snippets:, it is not really hard to do. But have great deal to help user explore the content, as well as showing a clear structure of your website.
13. Use Meta Tag, meta tag holds important role of the post. It summarized the content, so use it wisely.
14. Structured data, structured data helps better search engine crawl and collect information for your website.
15. Use optimized images, use a small size image but attractive as a picture paints a thousand word. Also consider the file name, "alt" text and title as it play significant role to drive traffic from image search.
16. Internal link building, if you have related content so don't be hesitate to link it to the post. But build only a natural link building, means the posts must really have relation one to another.
17. Fix broken links, never ignore this always keep you website healthy. Never confuse user and search engine from unexist content, try to redirect the links to a relevant page.
Social Media & Promotion
18. Onsite communication, always respond to comments and keep the conversations alive. This will keep your regular visitor.
19. Use Social Media tools, never miss a chance to get involved in social media. Use social share and bookmarking in a visible place of your site.
20. Tracking and monitoring, always evaluate your website regularly. Use google analytic to see your website performance, there you'll see improvements and what to fix in the future.
As You see, most important points of this SEO guide are in the On Page Optimization. This means above every factor, the contents have the greatest role in SEO. They say "Content is King", so pay close attention to it. Finally, I finished the post. I hope this 20 Quick SEO Guide for Beginner will help You in optimizing your website to get more exposed in search engine.