I have searched a lot and implemented many many Regular Expression in my .htaccess file but can not succeed. How do I find a generic way that make my URL SEO friendly?

Currently this is in my .htaccess file:

   RewriteEngine On
   RewriteCond %{REQUEST_FILENAME} !-f
   RewriteCond %{REQUEST_FILENAME} !-d
   RewriteRule ^(.*)$ index.php?page=$1 [L,QSA]

What I need to do is that I have a URL like this:

   http://localhost/abc/index.php?page=boats_for_sale

I need to change it to

  http://localhost/abc/boats_for_sale

Similarly, I want to hide all query strings in my URL. How would I achieve it?