If I were in your shoes, I’d focus on two things right now: building hands-on experience with a smaller property like that duplex and surrounding yourself with people already playing at the level you want to reach.

They will overnight you a check that is counterfeit/stolen and tell you to use it to pay for the appraisal, except "they dont know what it will cost" so they "accidentally" send too much and expect you to wire back to them the "extra."

In your shoes I’d definitely connect with others in the San Diego area who’ve already done ADUs — their real numbers and lessons learned are gold.

I can definitely relate—I was once in your shoes, looking to break into real estate while juggling another career. 

It gives you focus and makes it much easier to recognize the right deal when it comes along instead of second-guessing everything.I’ve been working with newer investors in similar shoes and I’ve found that having someone in your corner for accountability and guidance really speeds things up.

Put yourself in a buyers shoes, if 100 yr old homes aren't the norm you made have a hard time flipping it.

One thing we've done and recommend (but few owners want to pay for) is to install cameras to monitor common areas.Inevitably, a tenant or two often abuse their common area privileges by leaving trash, shoes, plants, etc. in common areas and it's nice to know who to hold accountable.Regarding building checkups, it's great if cleaning & lawn help can be trained and motivated to alert the owner/PMC on issues.

In your shoes I highly recommend saving and educating yourself on the market, attend meet ups with local real estate investors, get the pro account on this platform so you can use and get good at analyzing deals on the calculators.There's several books on this platform that you could educate yourself with.Hope this helps :)

Most investors in your shoes don’t win on cashflow—they win on forced appreciation + tax benefits.

Forums like this are a great place to connect with experienced investors who’ve been in your shoes.