I think the hardest part was trying to clean the flux off of the board, and I never did get it that clean.

I chose to use sockets for the relays, and at first it had some weirdly inconsistent behavior. Removing and re-installing all the relays fixed it, though.

I went very slowly and checked my work as I went. I don't understand the circuit well enough to debug it, so I was very motivated to work accurately.