There seems to be a lot of confusion on this.
I check (on the web) numerous county clerks offices from many states.
It appears that the only thing you need to be concerned about is if you mark a straight party ticket and then write in the name. Once, you write in a name, the straight party ticket becomes invalid. So, just mark every selection individually and there should be no problem.
That is what I always do. I never vote ‘straight ticket’ and my CC lives down the street so I am aware of State and local laws.