I have done a handful of flips using cash, partnering with friends, and making it work. 

A friend of mine had a similar journey - they turned their old home into a rental property and soon realized they loved managing tenants and exploring ways to add value.

Do you build it with the intention of renting it or just for family/friend use?

They will get in touch with the property manager, let them know a complaint is filed, and typically give them an opportunity to make things right before opening an investigation.Have your friend look for a new PM immediately.Start by going to www.narpm.org to search their directory of managers.

This specific deal was a close friend's apartment that he was renting.

From a tax perspective, are there countries that are more friendly when it comes to tax advantages than others?

I personally know both @Jaclyn Cano and @Wale Lawal and can confidently say both are great and VERY Investor friendly!

At 19, your friends may not understand your drive.

I invest in Boise, ID and do quite a few BRRRRs, LTRs and STRs- varying degrees of success depending on how much equity we can force and the type of back end financing we can find, but the tax benefits are great and it's a rapidly growing market and Idaho is probably the most landlord friendly state in the nation. 

Inflation is your friend when you're not paying the heat and electric bills.