I've always wanted to get better at writing in english (my first language is portuguese). Unfortunately I'm too perfectionist to post things to my public blog regularly, so a private journal is a good alternative.

Try to build a habit, it helps a lot. I write (almost) every day, first thing in the morning, on a full screen terminal window with Emacs. I write whatever I want and then copy it to my Dropbox folder.

Before starting my writing habit I was spending a lot of time reading posts like "11 ways to write good headlines", "33 tips to better writing" and "10 ways to foster your creativity". Much more time than writing, actually. FAIL.

So, don't look for websites or programs; practice more. Read good books and analyse them.