Start with flips that need minimal work (cosmetic stuff) to get your feet wet. 

For example, when it's purely a cosmetic rehab and you are just replacing things, not relocating them or redesigning them.  

If I had rentals with central A/Cs, I would make a routine of going by and changing the a/c filters myself. 

Some of the units are 100% ready to go, others would need paint and cosmetic fixes.

The properties are in decent shape in a great neighborhood, with minor cosmetics they'd look great.

And to be honest, what you said about furnaces and the Appliance Repair Program says to me that you aren't even replacing older systems in your "rehabs" which means you're doing cosmetics.  

I found going to campus every morning to be a nice break from my normal routine, and even inspired me to start a new routine of getting up at 5:30am to go to the gym.

Good, sounds routine, including the ordering it too late.

If this looks like a bad relationship already then my approach would shift from pleasing the tenant and encouraging them to stay, to taking a firm line and having no nonsense.Having said that it is relatively routine for tenants to come up with a few maintenance issues at the outset, shortly after moving in.

Looking at some of the comps, I think the house could be worth $125k to 140k after finishing some of the cosmetic repairs.