You should write on topics with less competition and topics that no one else has written about. If you do write on competitive topics, try to put your own "twist" on it to differentiate yourself from the others.
You need to use good tags or no one will find your hubs. I looked at one of your hubs under the best tab on your profile page. You're not using enough tags nor are you using the most appropriate ones. For example your hub is about computer viruses and specifically a Christmas virus, yet you are not using either of theses as tags.
Also, I suggest reading up on SEO. There are lots of hubs already written on how to apply SEO to hubs. Just do a search and you'll find lots of good tips.
Best wishes to you.