Security Issues (input and output)

I am new to CodeIgniter. Thanks for free registration.

I want to know the best practices for user input and outputting the data keeping security at the top priority that is how to prep the data to insert in DB and how to output the data in the HTML or JS. I want to avoid all known attack like SQL Injection, CSRF, XSS or any other.

I read about following but can't decide which one or combination is the best and when to use.
strip_tags()
filter_var()
HTML purifier
xss_clean()
csrf_protection in CI
htmlspecialchar()
Regex

Please Help.