- store private key in encrypted form so you can do decrypt/sign messages on web(really optional, I discourage this - think of you storing your bitcoin private key on a service like coinbase)
- lookup others' key and encrypt with their public key
- verify others' signed messages which message is signed with the key stored on keybase.io
I'd recommend just use decentralized SKS keyservers - just use "gpg --send-key (KEYID)" on a terminal (assuming you are on GNU/Linux) and it's all set.
ps. If someone wants Keybase.io invitations, feel free to send me a PM after reading this.