Hair gets damaged due to mechanical stress due to vigorous repeated combing, blowing hot air for drying, straigthening etc. And also due to sunlight, pollution and other environmental factors. It becomes dry if nutrition is not good.  So avoid all hair styling machines if you want healthy hair and eat healthy food. Use sulfate free shampoo and conditioner. Use leave on serum after bath on wet hair. Short nail is not a problem. Growing nail longer is not healthy for anyone as they harbour harmful bactetia. For  Blackheads steam face for 2 min and remove by black head remover which are available in the market. Use non oily sunscreen