I have made previous improvements while living there over the years totalling $21,000 in CapEx and repairs since 2013.I have two options I see and I am trying to figure out which would give me the best start on building my property investment business.

Looks like you are set up to increase cash flow and with just time and slight improvements over time.  

@David Sisson When I’m presented with a somewhat frivolous request for an improved article when the existing article is properly functional, I either decline or I say that I can bring in a new one, but doing so would require a rise in the rent.

You'll also want to know the available operating reserves for capital improvements or maintenance of the HOA and community rules and regulations before closing the deal.

Rehab estimates though you need to have a knowledge person go through the property and determine what needs to be done and what you might want to do to improve the property's value

I always look for ways to improve a house when I walk in.

We are living in it temporarily while we make improvements to it (it's in another country where home improvements and repairs can take a really long time), we moved in at the very end of 2019, and plan to vacate to rent it out again within a few months.So since we are currently living here, would the vacant period preceding our occupation also count as personal use ? 

There is enough uncertainty as it is in this business so you want to minimize variable expenses, so that most of your expenses are fixed.It is always easier to bring in an additional dollar of income than it is to reduce a dollar of expenses, so when improving NOI look at the income side first. 

Make sure each deal you improve parts or all of your process and you'll be able to find an efficient way to identify, qualify, finance, acquire, and manage your deals.Find a way to get your first deal with the resources and network you currently have and through experience you'll expand your knowledge, skills, resources, and network as you go.

I'd also start building some real skills for home improvement as far as simple repairs or replacement techniques so I had something to offer others as either A. help and offer that as my sweat equity or B. jobs, to save more investment moneyI wold start looking towards longer term plans to make money to use for investing, myself, I'd save some more so I could become a notary at 18 and build a notary business as soon as I hit 18 to funnel into my RE plans, I think in CA, it's about $500 total from start to finish to become and Notary and loan signing agent.