When you say "nothing", so no lights or anything on the dash?
First is to make sure the battery is up to the job, should have 12.5 volts anything under 12 it needs a charge or be replaced.
If the battery is charged then I would pull every connection and clean them really good.
No lights or anything a bad connection on either side of the battery could be the cause.
Ground should go to the motor / trans, to the frame and to the body.
Pos. of battery to the relay, out of relay to lug on starter.
The relay needs to be grounded to the body and why the body needs to be grounded.
If the ground to motor / trans is bad no lights / start.
Dont forget to clean the battery connections.
Check that all out and let us know what you find.
Dave ----