"How can assisting others increase my traffic? I know it is a nice thing to do, but does it increase traffic?"

Here is an example from my own personal experience that shows that it does:

When Nick (mentioned earlier) told me where I could find a wordpress plug-in I wanted for my blog, he won my goodwill. I posted a short article about the plug-in, mentioned his site, and included a link to it. I even went to some other Japan-blogs and said "Here's a plug-in that Nick from longcountdown.com shared with me, in case you want to install it."

The point? Assist others and most likely they will talk about you, maybe even link to you.

And even if they do not they will certainly at least be thankful (and apt to help you later on). It is all about building relationships.