The McD's ads are fun.
>>2236464"Cagliostro" is narratively a bit of an outlier because Miyazaki was writing a coda to his run on the show, so Lupin is more mature and less of a devious skirt-chaser that he is in 99% of the franchise.
As far as other movies - "Mystery of Mamo" is fun but gets really crazy, kind of emphasizes how far the series can go in contrast to Cagliostro. "First Contact" is a TV special prequel that's a good intro.
For the first three TV series YMMV on what you enjoy due to their age and varying tones, I'd suggest finding a list or two of recommended episodes and jumping around to get a feel of what you like before committing to watching any show front-to-back. The modern TV series are a bit more linear but you can still comfortably watch many of their episodes piecemeal, too.,
