Most people especially those with no technological background can't understand how can a decentralized currency with no central authority exists.
So here explain about blockchain, how and why does it work, but try not to overwhelm them with details.
Once they have a basic understanding how everything works you can start explaining why is it profitable to invest in bitcoin, tell them about alt coins, make them understand that not every other coin is like bitcoin, explain some projects that you know about and that you are invested in, share you experience.
Most importantly if they are looking to invest tell them how the process with exchanges and wallets works. Put them on high alert for scams (if it seems to good to be true it
Introduce them to ICOs, explain how it works. While telling them about ICOs mention scammers about a gazillion times more.
If possible sit down with them and help them with their first investment, I remember everything was weird to me the first time.