Yeah, I couldn't get the hang of the metal clips either.
I use two claw clips, the size that fit comfortably around my thumb. I just place one in front of the other along my part, so that each one is pulling the hair on each side of the part toward the center. Placement isn't very critical. I just leave them in while I diffuse and then take them out. (Well, I have been know to forget them and walk around with stupid-looking clips in my hair...)