Consider your resources
There are two dimensions when you're assessing your resources: short-term and long-term. The former usually refers to a period of up to a year, and the latter is considered for events occurring after that.
So, let's say you have a team of three, and you've been offered a new project that requires at least seven employees, including two with a set of skills your team doesn't possess. The question is, should you decline the offer or accept and ask for a delayed start so you can gather the necessary people?