One of the first tools taught in marketing courses is the SWOT Analysis’a useful tool for any money-making strategy.
The SWOT doesn’t end at marketing despite its lack of mention anywhere else, however. In evaluating any money-making or -spending decision, the SWOT can better prepare you for the future by focusing on the key, well-rounded areas worthy of your attention.

SWOT Analysis:
S- STRENGTHS within the company
W- WEAKNESSES within the company
O- OPPORTUNITIES within the industry/economy
T- THREATS within the industry/economy

As you can see, the strengths and weaknesses consider an internal analysis of a possible proposition. What tangible and intangible resources are at your disposal? Any internal drawbacks that might prevent success? (Simplified example: The potential real estate property seems to have a great foundation, but the roof leaks.)

Unfortunately, you cannot operate a monopoly, and external competition and influences do exist. Evaluate how these conditions can hurt or help you. (Simplified example: The neighborhood looks really promising, yet the city also plans to increase property taxes.)