EDIT: I wrote this just after I started learning but updated it with new resources and links just before I launched this site three years later.
This was my first ever exposure to code. I was a little intimidated at first, but, you know what, it wasn't actually that bad —even for someone who had never written a line of code before starting out. (I last had anything to do with making a website in 1997 using Macromedia Dreamweaver).
No, learning HTML was in fact pretty straight forward. And, actually, as it seems that HTML5 is now pretty standard and widely supported, around about now seems like a great time to be learning the language. I love the focus on pure structure and semantics
(using tags that add meaning to a document layout), while keeping styling separate.
How I Approach HTML
If you've ever added formatting to a document using the numbered headings or other formatting options in Word quite a lot of HTML will quickly make sense. Of course, there are a fair few HTML tags to get familiar with (in fact as you dive deeper there seems to be an almost never ending list), but it really is manageable to get your head around the small number of most useful tags pretty quickly.
I really wanted to get a good understanding of HTML and feel comfortable with it before moving on to CSS. [EDIT: looking back now I can say with confidence that this was time really well spent. HTML is the foundation of everything and really worth spending time with before moving on. Having a solid basis has really helped making my sites more accessible, applying CSS correctly and managing HTML with JS.]
Resources I Used
I mainly learnt HTML through courses on lynda.com (now LinkedIn Learning) which I got free with my day job. I really, really liked the courses by James Williamson, who sadly died a couple of years back. I found HTML Essential Training and HTML5: Structure, Syntax and Semantics particularly useful. You can still find some of these courses if you search around a bit on the Internet.
[EDIT: Jen Simmons has a more up-to-date HTML course on LinkedIn Learning which is also really worth checking out if you have access.]
I also found the HTML and CSS book by Jon Ducket a very useful reference. It's a little dated now with regard some aspects of HTML5, but it's beautiful to look at and a joy to read. I continually referred back to this book as different aspects of HTML were covered in the courses I was following. I'm currently in the middle of a couple of lynda.com courses on images and I am still referring back to this book.
Later on, I also found Learning Web Design by Jennifer Robbins. I really, really like this book. In fact, if I were to recommend one book that I've come across for learning web design it would be this one. OK, it may look a little more textbook than the Duckett book, but its very readable, really comprehensive, up-to-date (at the time of writing this), and is still pretty nice to look at.