More symptom descriptions would help. BUT, based on my past experience with my Dodge Charger, you have a bad starter solenoid.
I think all starters work the same. The solenoid has 2 coils, Both are activated when you hit the key to start. One drops out when the started switch is activated leaving the other to hold it in position. If one coil opens, there isn't enough force to pull the bendix in all the way. After a few tries you get lucky and it gets all the way in.