Vision and belief of what a house can be is probably the hardest thing anyone can develop.
If you partner with someone with at least 100 deals under their belt, they should be advanced enough to possess this skill set. The pictures I have put in place should be able to help create this vision. I can take an ugly house all day long, and depending on the budget, can make it cute, pretty, hot, or smokin hot!
I have the vision, and can see through the ugliest, and scariest of all properties. The first thing I have to look at is what is my exit strategy? I am not going to put a ton of money into a property I am holding as a rental. If I am going to owner finance it or do a rent to own, I am not going to put even as much as I would if it was a rental.
If I retail this property, my rehab will change depending on what the local economy will support for that type of house, how long I want it to sit on the market, what type of buyer I am trying to attract, and the type of loan the buyer will need to get. A lot of historic areas, have all different sizes, price points, features, conditions, and so you better know what you are comparing yourself too when you are pricing your house for a retail sale.
Now back to vision, look at as many houses as you can and eventually you will get more comfortable with your vision and belief. The following example is of just an exterior of a house.