To get started you'll probably have most of these items already laying around your house, if not you can find everything you need at your local $1 Store or Craft Store. This is what you need to make one dozen tissue paper flowers. One piece of tissue paper makes one flower. It's easiest to make the flowers in multiples of three. Adjust what you need based on how many flowers you want to make.
12 Sheets of Tissue Paper (20"x26" or 20"x30")
12 Pipe Cleaners or other Flexible Wire
Ribbon to decorate the Vase
Scotch Tape to attach the Ribbon to the Vase
A Ruler or Measuring Tape