Here's some possibilities:
- Your battery terminals arent connected tight enough, clean enough, or the ground isn't grounded well enough.
- Starter solenoid is bad, which means replacing the whole starter. If you hear a click come from the engine bay when you turn the key your solenoid is fine, and your starter motor could be bad. If no click, then possibly ur solution.
- Starter relay is bad, you can check by switching it with any other relay in the little box in the engine bay.
Tips for removing/installing starter:
It's located right in the front of the engine bay where the transmission meets the engine, you can follow the wire from the positive terminal on the battery down directly to the starter. There's (2) 14 mm bolts that mount it up to the engine (actually transmission), remove those and the starter will pull out and down. Then there's a 12 mm bolt that holds the wire from the batter onto the post on the starter, along with a clip connecter that you just squeeze and pull off. Remove those, connect them to the new starter, put the new starter back up on the engine (transmission) and bolt it back in.
Well those were more of instructions rather than tips, but you get the point.