How can i improve my html coding skills?

MonsterMMORPG

I am planning to become expert at twitter bootstrap and responsive design

what do you guys suggest?

[Michael]

Well, how far along are you with HTML, CSS, and Javascript? These are the foundations. You're not gonna get too far without a good understanding of these.

I'm a fan of MDN, and they've got a page that will hopefully help regardless of your skill level: https://developer.mozilla.org/en-US/Learn

I've managed to get some good use out of bootstrap mostly from these two pages:

http://getbootstrap.com/getting-started/
http://getbootstrap.com/css/

And this is the second time I've said this in the past day, but start reading blogs and magazines related to web design so you can keep up with where the web is heading. It's a http://smashingmagazine.com and http://css-tricks.com are good.

Reading tutorials, guides, and articles will only get you so far. Put it to work. Do some projects. Make mock websites if you don't have any real projects to do.

Nbsp

Go to websites you like and use chrome developer tools to see how they put their CSS and HTML together. Maybe even go in and change some things up on the page to see how it's affected.

Spectral Swallow

I actually code for a living and almost all of it was self taught. I did go to a vo tech for webpage design, but it was a huge waste of time (the teacher ACTUALLY told us to use flash for menus. =D ). So I wouldn't recommend that.
A lot of my learning actually came from either just reading through w3schools tutorials (which are hit and miss on some topics).
And checking out stackoverflow's question section.
But really the best way to learn is just to practice. Determine what you want to do/make and then try and make it. When you hit a wall, google the answer.
Also if you haven't already, download chrome for testing purposes and make sure you're using a localhost (xampp). It makes testing and view your code MUCH easier.
And if you're anything like I was starting out, this code:
<meta http-equiv="refresh" content="5; URL=http://www.yourdomain.com/yoursite.html"&gt;
will automatically refresh the page every 5 seconds so you can see the changes easily (if you're using dual monitors).

And FINALLY, eventually you WILL need to learn php.
If for no other reason than for the 'include' command. For example if you have 30 pages, instead of updating 30 copyright dates (on each page) you update 1 include file.

Hope that helps.

[Michael]

Doesn't have to be PHP, but server-side languages are useful if you want to go beyond static sites. There are client-side "includes" nowadays, too.