Check to see if you have power to the trigger on the starter solenoid, follow the + battery cable to find it, you'll have either 3 or 4 total wires on the solenoid, 1 big red from the battery, one big red to the starter, 1 small wire from the keyswitch and 1 that goes through the safety switches.
On the trigger wire you should have battery voltage, or just a little less when the key is in the start position. Or you can set your meter to DC 20V, + lead to the starter side lug on the solenoid, and other lead - to a good ground (Frame bolt, etc) when you turn the key to start check for voltage on the starter side solenoid post. no voltage, either a safety switch or bad solenoid.