is there a trick to clean nespresso machine?

No real trick, just descale it properly and regularly. Use a descaling solution or citric acid rather than vinegar - Nespresso recommend against vinegar and it's a pain to rinse out. The descale mode is different between Original and Vertuo models, so check the button sequence in your manual. In between, run a water-only shot every few days and empty the capsule bin and drip tray before they go mouldy.