Let's see:

 - **Ask a question**  
   If it's good you get THREE upvotes... and you can upvote.

 - **Post ONE good answer**  
   Have it voted up, just TWICE, or get it right... and you're there.

 - **Link an existing account**  
   If you already have a Stack Exchange account elsewhere with at least 200 rep and you link it, you get 100 reputation!

It isn't that hard to get 15 reputation. Getting that reputation basically means that you've bothered to make an effort and have contributed to the site.