I wish I had spent 80% of my time doing all that stuff and 20% of my time going out with friends, doing a bit more traveling, going on a road trip, etc.  

Start with a foundational BiggerPockets book (keep reading more of them and check out the list @Jason Reynolds provided, great stuff on there), listen to the Real Estate Podcast, and read Blog posts.

Even if it’s boring stuff like empty rooms and blank walls.

I'm glad you're on this hard, scary stuff using your picture even. 

I see a lot of stuff before there is an agent involved.

Yes, I will move my stuff into the place, but it will be listed as my primary residence.

My rental properties fund my children's 529 plans as well as their current educations and fun stuff.

It's something simple but it can be part of first impressions if someone does drive by.You can look toward some very simple and inexpensive staging type stuff, such as trying to make it seem more personal and inviting without making potential buyers feel like they're invading someone's space or subject to someone else's opinionated style choices.

Only thing I’ll be paying for is really lawn care and saving money for other stuff in the future vacancy , repairs and so on .

One of our tenants is for lack of better words, a hoarder and the unit is not clean at all and filled with stuff.