Hi @technovedanta! Here's a cheat sheet for markdown.

http://assemble.io/docs/Cheatsheet-Markdown.html

To this day I am still learning how to best format my posts. Steemit does support some HTML but not all of it - and I have yet to find a way to underline text, though I've managed to learn how to do subscript, superscript, and strikethroughs...but I never use them!

Headers are probably the easiest thing you can implement now. It does support the < h > tags but all you need to do is put a # at the beginning of your paragraph/sentence.
One # is equivalent to the h1 tag.
Two # is equivalent to the h2 tag...and so on.

Use a * before and after your text that you wish to italicize
Use two * before after after text to bold
Use three * before and after text to italicize and bold

I'd be happy to help you along if you have more questions. And if I can't answer them, I'll find someone who can
All best & Good luck :)