I use Perler or Hama Beads (in America it is Perler, in France the most famous is Hama, and Ikea is also doing these kinds of pearls nowadays), I choose the character I want to do, place the bead according to its design on a Perler/Hama board and then I cover the board with Ironing paper (or tracing paper, barkery release paper) and iron it! xD