I've heard a number of people say that to grow in writing, you must read a lot. One person said to read all sorts of different things, easy and difficult books. Another said to read challenging philosophy books.
I'd say a better piece of advice is to do things that include not only that but watching TV, browsing the internet, visiting new places, talking to people, and just do what you'd normally do. The reason this will help is experiencing life--the very topic most all writing is about--is what you'll be writing about. If you write something more abstract and philosophical, it still can benefit when you write in a way that relates to life, with examples, analogies, and metaphors. And when you can use language you hear everyday.
The best writing is sometimes the simplest: write what's on your mind. Stop waiting and saying "Oh, wait, I have to do one more thing to get better." Sometimes that can be procrastination or fear of not being good at something.
Reading books on writing is helpful, but you also need to practice and write. When you actually write, you start to see what you like and don't like in how things are worded or titled. You start to develop a "voice." You remember what you added or changed last time and start to feel more confident. You see what works.
If you're blogging, I've heard many people recommend writing something that helps others. Write more than what you did today or an opinion you have that might not help someone else.
