valid passport (valid at least until 6 months after your stay)
insurance form E 128 (you can get it with your sick-fund)
form E101 (social insurance) ­ from Crazy Company GmbH

good gym sneakers and maybe sandals with straps (not flip flops)
track suit for the course: short/long pants, pullover/jacket, shirts swimsuit, bathtowel
cosmetic articles
dance shoes (if you don't have: boys-"elegant"black or dark shoes/girls: the same, with heels
jacket for pre-and afterseason time (could be fresh!)
possibly your mobile phone (rechargeable SIM-cards can be bought locally )
„elegant“ clothes for the evening (pants, shirts, skirts...)
white T-Shirt, black pants, white shirt

apartment? - sublet ? give notice?
fix costs- f.e. sick-fund - standing order?
if you travel to your originary country: inform yourself about military service ! (only men)