I love the unique look of child-coloured wrapping paper for gifts and it doubles as an activity the kids enjoy too. You can get a roll of brown (Kraft) paper from places like Officeworks, Kmart, Target, BIG W and stationery stores. 30 metres cost about $15 so it goes a long way.
Felt pens, ballpoint pen, pencils, oil pastels, and crayons all work. Paint also works but there that extra step of allowing it to dry.