My car will randomly not start

I am having the same issue, sometimes the car will start but usually will not. I know both the neutral switch and the 'switch' for the clutch were replaced. I looked and the battery terminals are fully seated. The battery is like new. is there maybe a ground somewhere that needs to be checked? Also the starter was checked in a shop and is just fine. I do seem to have trouble getting the key to turn sometimes, is there a known problem with the ignition system?