The greatest bit of wisdom I could share is to simply write everyday. This is advice that I need to follow too, but if you can write something everyday, anything at all, you are a writer.
Write a poem, a story, a diary entry, or a tip in a writing blog about writing something everyday. Write whatever you want, but write something. This will make the difference between launching the career that you want and spending your existence in a job that you don’t really care for.
If you write and it’s terrible, write more. It will get better. People argue that you’re either a writer or not a writer, but you have 365 days a year to practise. You’ll get better in no time. If grammar is an issue for you, take classes. That doesn’t clear up on its own. If the writing is too concise, not concise enough, or just no good, read other work, get inspired.
You will get there if you write everyday.