You may want to consider updating the electrical panel at the same time depending on the age, and manufacture.  

And it really opened my eyes to the nonsense perpetrated by these "anti-gentrification causes".We'll see how well the vocal few take my 5,000 postcards I'm about to send out that'll cover about 50% of the properties :-).

When you ask a bunch of old farts what they would have done at your age knowing what they know now, you're really going to get some good stuff.

The 50% rule a good smell test, but the age of the properties, the differed maintenance, the utility break down, rent amount, etc will all change the percentage of expenses on income. 

I have been reading about real estate since I was fifteen but I never had a chance to put into action due to my age; however, this summer I took an internship at some brokerage and I have decided to become a real estate agent.

Be prepared for delays,lots of them.Rain and snow(if any) can ruin the days you had scheduled to repair the roof,paint the exterior,repair or change the landscape or driveway,etc.Also,if you're trying to sell single family homes beware,parents don't normally want to move their children to a new home and possibly to new schools in the middle of a bitter cold winter.Only if you price the home well below the after repair value and give them some instant equity will you get good enough offers to accept.Even in warmer weather states like California and Florida,finding multiple offers from families with school aged children can be difficult.Be prepared for the home to sit on the market for 90 days or more until it gets closer to the end of the school year.

I personally struggled with this issue myself at your age when I first started investing in real estate, so I'll briefly share my take on this issue.

That work up here is 8 or 9 ft deep and they have to use anti cave platforms...

Washer and dryers are must this day and age correct?

@Devang Vora Capex depends on a few things to my understanding; how long you plan to keep the property, the age and state of any of the big ticket items, etc...