For me, Step #1 is just "read a lot." As you read, you expose yourself to literary techniques, words, turns of phrase, narrative framing and structure, and many useful writing elements.
Step #2 is "have a desired emotional effect you want to have." For me every piece of writing is driven by emotion; I know what I want the reader to feel. It is all built around that. Then there is some factual/logical piece of it, that either supports the emotion, or is supported by the emotion. For instance, I want a guy to go open more girls. So I will write a piece on opening, to give him a fresh new tactic he can use for that, meanwhile I will write the piece with an emotional thrust designed to excite him to get out and open more girls.
I had a few flashes when younger due to just #s 1 and 2. But I still put out a lot of middling quality work then too. So when I was 18 I decided to start writing short stories every day. I did that for a while, hewing to the style of my favorite fiction author (H.P. Lovecraft). I started off very derivative, but wasn't worried about it, since everyone starts that way (and in fact, Lovecraft's early stuff is itself derivative, of Edgar Allen Poe, Lord Dunsany, etc.).
I talk about my approach to structuring articles in this post. Hector also has some great tips in that thread.
I will also say -- participating in forums made a big difference for me too. I spent a lot of time replying to guys' posts on forums, racking my brain for worthwhile and useful things to point out, to both give positive feedback and valuable critique. I did that consciously, to improve my ability to analyze, to write well, give quality feedback, and be able to come across as both knowledgeable and credible. It gets easier the more you do it. Forum posting replies led to making original forum contributions... which I did not want to do unless I had original ideas or tactics to share. That led to writing articles. If you read my article history on Girls Chase, it starts off with me doing mostly shorter articles, then progresses to longer and longer ones. It got easier and easier for me to write longer pieces as I wrote more.
When you're starting out, focus on short, easy stuff: short stories, forum posts/replies, anything that allows you to craft a full post with not too many words. This will teach you structure, pacing, framing, all the other stuff you need.
As you get better, and can write faster, and think as you write, you'll be able to do longer and bigger pieces, and complete them faster and faster, too.
Break a leg (quill), man!