Well the paper is usally Sathmore 400 series watercolor paper(cotton is better but way more expensive, Fabriano or Cartera Magnani), for the paints i use anything from MaimeriBlu, Holbin, M.Graham, Daniel Smith to Grumbacher Academy and Windsor Newton Cottoman series. the 1st 4 are quite pricey but work amazingly well. the last are cheaper student grade but get the job done.
For brushes i use a series no longer made by Windsor Newton 'Cirrus' Kolinsky Sable, and a newer 'One Stroke' same brand and hair just new and being made. The Kolinsky sable holds the perfect amount of water and paint for watercoloring, tho a squirrl brush isnt bad either but can be a bit floppy.