First, you want to make sure you are writing hubs that people want to read. Choosing popular topics really helps. How-Tos and facts a student might look up, for example.
Then you want to write a quality hub that provides the information that people were looking for. Give them additional information that isn't on every other website about the topic.
Be sure to check for spelling, grammar and other typos.
You need to make sure that the search engines can find your hub, so make sure that the title clearly uses the words someone would type in the search engine to find that hub. Also use those keywords several times throughout the hub. I had a book review hub that didn't use the word book or review at all, and had to go back and edit it.
Last but not least, you need to market the hub. Make sure you put links on each of your hubs to some your other hubs about the same topic. Send links to your friends and family so they can look at it. You can consider having another site - a blog for example, where you talk about your hub with a link, so that you can get some free advertisement.
You also have to have patience. It takes time for a hub to age properly, and after you have done your part, you have to wait. I like to write other hubs while I am waiting.