What are some best practices when driving for dollars?

We are just starting out. 0 flips so far. Last night we drove for dollars in our market. Our strategy is to scour sections of the city one at a time, take some addresses down and then check comps around that area. 

Two part question. 
What clues do you look for that indicate a good flip? 

If a property is simply outdated, never really touched on the inside, is that alone worth a flip? Or should we be looking specifically for those overgrown, run down roof and siding properties??