High Key and Low Key v1

The rationale of the fourth assignment is that "High key and low key photography deliberately shift the key tone is not only to make an image lighter or darker overall, but also to signal a mood or feeling to achieve the desire visual effect."

We are required to capture 2 photos using straight photographic techniques:
1. High Key
2. Low Key

These were the photos uploaded to picasa:

High Key

f/8, 1/5 sec, 38mm, ISO-1600, +2 step
Comments: Overexpose

f/10, 1/40 sec, 38mm, ISO-1600, +2 step
Comments: better than the first one

Low Key

f/5.6, 1/60 sec, 105mm, ISO-1600, -1 step
Comments: Mid Key

f/5.6, 1/160 sec, 105mm, ISO-1600, -2 step
Comments:

I find that this assignment was the most challenging one! After I took lots of photos, both my high key and low key still failed and I don't really know how to get the right one :(