Meg Waite Clayton
Write. Revise. Repeat. Repeat again and again and again. Submit. Toss the rejections aside. Revise again. Submit again. Repeat and repeat and repeat long beyond the point when any reasonable person would have given up. Your own mother will start to doubt you. Just ignore her and keep writing and revising and submitting.
Seriously, I host a blog where I have hosted literally hundreds of amazing writers and every single one -- even National Book Award winners and bestsellers, even the ones who look like overnight successes -- write about the rejection they had to endure. If you aren't being rejected you aren't reaching high enough.