I'm a contractor(outsourcer) for several agencies and other independent consultants but the thing is that they approached me through my site and ads.They send me projects every month but I want to scale it up.

I find it difficult to approach them first. I don't know how to make them see the value in outsourcing the mobile design work(in my case) to my team or simply offering this service(which the don't do yet) to their existing and future customers for a huge commission(they keep the clients, we're just working behind the curtain). Also, we only do custom work so that's a plus which adds good value to the offer right?

I only tried email approach and got only few responses back from couple thousand emails sent by hand so clearly I don't know how to do it right.

I'm interested also to see is anybody got good experience with this.There's a huge market for everyone so I think that getting ideas together could create a good strategy that we could use.

Edit:
thanks MobileMarketingMogul, but I hope this thread becomes a reference for people in our situation by contributions of the experienced players

Maybe you should also consider networking with other marketers/clients in your niche by interacting on other forums within this mobile marketing niche as well.