Well, I'm definitely no authority on making money on Hub Pages. But I have made some money, and it is increasing recently as I adjust my approach. Girl gone strong makes some good points. Let me also add you need to write a LOT of hubs. Right now I've written about 60 or so, but I could have easily written dozens more in the time that I've been here.
If you look at all the successful hubbers who make a lot of money, they all have over 100 hubs, and many have several hundred. They also write on a variety of topics, instead of just one. Usually at least 3 or 4 major topics.
The ideal length of each hub should be roughly between 400 and 1000 words or so, in my experience. Anything shorter or longer than that is not attractive to most people. This is good in a way, because if you have 1500 words to say about something, you can break that up into 3 or 4 hubs and get four times the amount of search engine attention.
Also pay attention to details like titles and headings in the hubs. You can try different titles containing different keywords that will attract more people. And do make use of the headings in each capsule when writing a hub. Don't put your section headings as bold text inside the capsule, but rather put them as the heading of the capsule. Think about those keywords when writing the headings too.
And because I am a grammar nazi, everyone should edit their text. Do not have any grammatical errors or misspelled words in your articles. Try typing the whole thing in Microsoft Word and seeing the mistakes that the program highlights before posting it.
All of these things will increase your hub score as well. Just focus on the writing, and the scores will come naturally.
Writing well is a journey. I have learned a lot and my writing (and therefore earnings) have improved a lot just in the last year. One has to write hundreds of thousands of words to really get better over time, to attract more readers, to be more persuasive, to communicate better, etc.
A lot of more technical information like how to link text to another website or how to move capsules around can be found in Hub Pages help and tutorials. Or just experiment and explore the system.
Hope that helps.