I've been happy with this bike. Is there anything I should think about in terms of upkeep or safety on this bike.

For upkeep, all the bearings, headset, bottom bracket, axles, should be cleaned and greased if you don't know when it was done last. Chain, chainrings, and freewheel could probably use a clean.
Safety, get some new brake pads, Kool Stop if you are going to ride in the rain.

I like the old secondary brake levers, a/k/a suicide levers, and find them useful for a lot of my riding. If you’ve been using the bike a while, you've probably already done this, but get familiar with how the bike responds to braking on each set of levers, preferably enough so that you internalize when to switch down. And of course, better pads are never a bad thing.

How long have you had the bike? Are you the original owner?

Just from the looks of it, that bike needs a cleaning from the top down--and I mean a deep-clean--remove the chain and degrease; deep-clean the rear cogs and chainrings. I'd definitely consider servicing all bearings as suggested. Probably could use new cables too. Definitely new brake pads. Maybe new tires--again, it's hard to tell if they're dry-rotted from these fairly blurry photos.

Thanks for the advice. I bought it a few years ago from a New Jersey bike dealer, "Zach" who operates out of a UHaul unit. I have no problem with grease and grime, rust is the primary threat to the longevity of bikes and mine has been in a low humidity apartment except when I go out and take a 10-30 mile ride. Probably the brake pads should be replaced as needed.