What should I know before starting a website?

Finding a domain:

Finding a catchy domain that best represents your content is a little more difficult these days.Short and sweet is usually the key to success with most good domains, but it all comes down to the content you’ll be providing in the end

Coding:

Basics of HTML, CSS, PHP and little bit of Database ( MySQL)

Web Hosting:

With most products, everybody has their specific preference when it comes to a good host. People are usually looking for a good price, good uptime, good customer service, and a good reputation

Hosts to look at:

WH

Design:

Check out the sites below for good design info:

SEO:
The most important thing is knowing how to make great content. That content can earn you authority with search engines and help you get back links which will ultimately help you rank.

The last bit of advice is keep things simple. Make sure that you have a goal that you want your visitors to achieve when visiting your site. Make that goal as easy as possible for them