This is a great exercise, plenty of ‘room’ for expression.
I often think it is a good to have some sort of an idea for the design you want to create. Once you have a general idea set about securing the first two branches, which preferably produce three points of contact so it stands freely, other wise you will need to add the ‘third’ leg. Now you have established a free-standing form the remaining branches can be added at ‘random’ or in a more ‘planned order’. The final ‘sculpture’ should be an interesting form on its own. An added advantage is the ‘sculpture’ can stand on various points making it very versatile for future work in an arrangement.
Delighted with the form you have built, it is time for the ‘second approach’ where the form is placed at any angle in or over a container, which is the water supply for the fresh materials. Let your imagination run wild and create a fantastic flash of colour to highlight the branch sculpture