Paint thinner (linseed oil or any other store-bought oil painting medium will do)
Flat synthetic brushes: size 12, 8 and 1
For cleaning the brushes: paper towels or wet wipes. Solvent (white spirit or similar) is optional If you need help choosing art supplies for yourself, HERE you can find lists of recommended art supplies with Amazon links for your country. At the moment the lists of supplies are made for USA, UK & Ireland and Italy based students.