User inputs, clean and sanitize before sending to db

I've searched a lot of the questions here and I found that they either very old or suggesting using prepared statements PDO which I am not using. So I need your help please.

I have a small discussion/chat box where a user submit a message using a <textarea>

What I need is sanitize and filter the user input so it only accepts plain texts (e.g. no tags, no html tags, no scripts no links, etc). Also, it is important to allow line breaks.

Based on my reading I am doing the following in the following order:

1. trim()
2. htmlentities($comment, ENT_NOQUOTES)
3. mysqli_real_escape_string()
4. nl2br()

Is what I am doing is right? or I am missing something?

Also is there anything I have to do when echoing the data from the db?

really, appreciate your help and kindness

via Chebli Mohamed