This will be an interesting task and very rewarding. Nature itself supplies the answer. Some are objects with simple lines while others are more complex.
Lines are the basis for traditional arranging.
These illustrations will give you an idea of each. You will find many everyday, household articles useful as containers. Your amber-colored iced tea glass, an old pastel Easter basket or a used flower pot may take on a whole new life. Using a layer of sand on the bottom might be the simplest solution. Other ways are to use crunched up chicken wire or commercial products such as Oasis .