what should we do to write a good paragraph?

Answer 1

http://www.arts.uottawa.ca/writcent/hypergrammar/paragrph.html
Go through the items in the left column under the words Writing Paragraphs. This is one of the best explanations I've seen.

Here's another, for very beginning writers:
http://huertas.vms.lusd.org/Janeschafferhowsto.html