Hi Joey, big thing I wished I knew was how to do many of the repairs myself. Over the years, I've learned that many repair issues really aren't that complicated to figure out (though I've had water issues at a couple properties that even some plumbers could not figure out what was wrong) if you have the time and patience. So for repairs, I recommend you get clear on what items you are likely willing to deal with yourself and then leave the rest to a professional.
Regarding liability and injuries. Well some issues can be avoided by carefully screening potential tenants. Also, make sure your property is up to code and doesn't have any outstanding liability issues. I've had an agent from my insurance companies walk properties to look for any potential liability issues and I found that very helpful. And treating your tenants with honesty and direct communication, while providing a well maintained unit, and quickly addressing any of their concerns goes a long ways in preventing issues.
And then put in place whatever protection measures you can to limit your liability and also have enough insurance coverage. I, and my partner, always have umbrella coverage on top of our property insurance.
Wish you well in your journey - it can be very enjoyable. If you have any other questions, I'm happy to answer them.