The best way to have healthy hair growth is the basics for being healthy in general. Eat the right foods- especially fruits, vegetables, whole grains and drink plenty of water. Water is very important for hair and nail growth. Exercise, at least 30 minutes a day. And sleep is also very important it helps the growth of hair and nails. There are certain supplements thats can help ur hair be healthier for example Biotin. You also have to be careful what you put in your hair and what you do to your hair, avoid styling tools but if you need to use them use them as little as possible. Just avoiding heat and chemicals is the best advice honestly and the most obivous. And lastly you have to take proper care of your hair depending on the texture as well. Idk your hair texture but whatever it is you should find the correct ways to care for it, for example the products, conditioners and stuff that you should use for you specific hair. Hope it goes well for you 🙂