Spend time in the Hub Pages learning center then read other people's hubs and see how the hubs you enjoy most are put together. Always leave feedback if it is heartfelt, authentic and/or constructive and closely follow hubbers whose work you truly admire.
Write about what you know, love and are passionate about and once you get comfortable with the basics of writing a hub, try experimenting with the different capsules and other tech features that can make your hubs stand out.
I'm still a newbie, but this has been the path I've taken since joining 2 months ago, and so far I'm truly loving my experience here on Hub Pages. The community is wonderfully supportive and it's really stimulating and fun to get immediate feedback.