easiest way is to manipulate the victim in giving the password or get physical access to the router a lot of routers have a sticker with the password on it. Cracking wpa2/wpa is practically impossible unless the person who set up the network messed up the opsec.You can always capture the handshake and try using third party services who crack the password for you.In most cases cracking the password(if set up properly) will take centuries literately centuries but i have a feeling you already knew that.
Not the right topic for this I think
i want to know this too. anyone here with this knowledge?