It may seem like a mountain of information is thrown at you once you dive into the world of real estate investing but everything really falls under a few key issues. 

What is the cost of repair?
What is the market price?
What is the ARV (After Repair Value) ?
What is the net?
Keep it simple and everything will work out just fine. No one makes it big over night and you have to break a few eggs to make an omelet. Let's start with cost of repair. On the day of your first visit to the home you need to asses as much as you can in that hour. Everything broken can be fixed for a price so it would behove you to know an estimate. The cost may change so you want to add 10% to all your estimates just to be on the conservative side. Worst case scenario is you either don't buy the home cause the repairs are too much or you end up pocketing more money for your next investment. 
The market value can me best observed by your realtor. He/She will have their finger on the pulse of the market and will be able to quickly tell you what market value really is in its present condition and that leads us to ARV. 
At the same time your Realtor will need to tell you what the home can go for at it's best. Combined with all you know about the home at this point you are ready to find out what you will net if you take on the project. If the numbers on that one don't work out don't worry just keep digging around and you'll find the treasure.