The worst-to-first turnaround that has brought the Boston Red Sox to the 2013 World Series is largely attributable to their wise free-agent spending. Following the same keys they did this coming offseason could elevate most teams to the same heights in 2014.
General managers all have the same aspirations—acquire as much talent as possible for the lowest price.
The few that succeed from that perspective properly blend advanced statistics with personal evaluations; they factor in positional scarcity and only take calculated risks.
Specific spending strategies can vary a bit from front office to front office, but these are the constant guidelines that ought to be followed universally.