I suppose it takes a certain amount of energy and patience to be a good Auntie but what it really takes is a listening ear. Young people want, and need, to be heard.
The major difference between me and my sisters was that I had no inclination to marry at a young age. I was out having way too much fun exploring the world and all its offerings. I finally married at one month shy of age 35 and had my one and only child at age 38.
For any young person it's important to know you can support yourself both financially and and socially. IMO it's important to live alone and not only get to know yourself but build that strength of knowing your own capabilities.