What should I look for when buying a rental properties? Are there some indicators that are more important than others?

For sure you want to make sure there's cashflow, but what else? For example is there any way I can tell if the property hasn't really been maintained well and I'll need to put money into uplifting it?

Is there also some rules of thumb to assist me in finding less reputable numbers? That is, are there ways to tell when someone isn't being completely honest with their numbers and adjusting them in a positive way that will cost me money in the future?