Ventilation is a must...unless, you thinking getting high is cool. Might look great until you wake-up the next day with a bad headache and don't know why your paint job now sucks so bad.
Respirator is a good idea. Imagine how mush paint would be going up your nose.
just my two cents.
When painting/priming. You don't want to leave your finger on the trigger all the time. Figure out your spray path and you start just before you hit your mark. Make your sweep and finger off the trigger just pass the mark. Kind of a on & off sweep. You do the same on the back sweep pass. back and forth on off on off.
I thought I would put that in sense I didn't see it posted above.
Mike