For my first still life I actually repeated an assignment I did back in high school. The concept is that you use only white objects and have to use the light to create shadows and differentiate between the whites.
The second still was something I also wanted to try and it was really hard. You can see in my setup photo I had a pan fill with water and then a bag with a small hole to in it creating steady, even drops of water. The problem was getting the time right: taking the photo at just the right moment. I have a good 50 shots of just still water, no drops.