Write, write, write. If it is really something you want, you should always make time to write. Even if it is in the car while your kid is at practice (dance, ball, etc.), in the waiting room of the doctor's, or during your lunch break. It should be the foremost thing on your mind 24 hrs a day. Every time you write, you're improving.
Another thing is to get a critique partner, especially one who writes in the same genre or similar one. You learn so much reading others' manuscripts: such as what not to do and what you should be doing. You'll certainly realize how much you've improved since you began writing and can help others. A win-win for sure.