ok first up I love the composition of 2!
Now though you need to get the shots sharp - follow Flash Harry's advice - move back a little, and don't forget to stop down the lens - it might be able to shoot at f1.8, but the depth of field at that aperture and at such close distances will be so fine that only a small portion of the face will be in focus.
As this is my first 1.8 lens, I wanted to see if I could get the eyes "secluded" so to speak, but stopping it down to 2.5 would probly look better now that I understand it a little better. Thanks for the CC!
Shooting wide open with a fast lens is harder than it looks. Your DOF may be razor thin so you need to make sure you get the parts in focus that you want to be in focus. Of course, make sure you are not within the lens's minimum focus distance.
This would be a good time to use the continuous shooting mode on your camera. Fire off a burst of shots while slightly moving and trying to get the right focus point. Then when you review the shots, you can toss the ones that didn't hit focus and keep the ones that did.
unfortunately, my son moves around way to much to use a tripod. I could use one with my dog, but i have a $30 sunpack that wont let me get low... tripod is now at the top of my list for things needed. I bought a nice mono-pod for my hiking and motorsports though, thats been working out well. Although f5.6 at 180mph hasnt been working as well as i hoped it would, lol.