That is a great question. I have heard that some people earn a fair amount of money by monetizing their Hubs through Google. I was monetized through Google but was dropped some years ago when I was quite inactive. I hopped back onto HubPages after my leave of absence and discovered I had been permanently banned. Too bad. I think it might be a great way to earn a little extra through something I enjoy doing. Just keep writing about subjects that pique your interest and your writing will improve over time. It might also help if you gather a team of friends to read your Hubs and offer advice on how to improve. Most communities have writing groups. Join one if you want to improve your craft.
Enjoy the process and happy writing!