Cuda acting up. Turn key and nothing?

Forgot to add. One time before I cleaned the terminals off on the battery and tried it again and it started. But I dont think that is the problem because it is happening more frequently and the terminals are clean no corrosion. It could of been just coincidence. I'm by myself right now so if I use a screwdriver and jump the starter realy with the ignition turned on the car should crank the starter correct? That means starter relay probably bad. If I test the lead coming out of the relay to the starter and it is getting juice than probably the starter correct? I'll take a pic of the starter relay later. Thanks everyone.