For one, spending influences the amount of wealth someone has. That seems obvious, but to make the consequences apparent, the guide asks people to think about what they want to happen to the money they’ve accumulated. There are only four choices: Spend it down, keep it at the current level, preserve its buying power by having its value keep up with inflation, or spend or invest it to grow as much as possible.

Ms. Allred said few very wealthy people chose to spend their wealth down to zero — though she worked with one client who would be fine if that happened. But increasing wealth while spending heavily is difficult without additional sources of income. If a portfolio grows at 5 percent a year, for example, but inflation is 3 percent and taxes are 2 percent, there isn’t a lot of room for spending if you want your net worth to grow.

The guide also recommends thinking proactively, not reactively, with spending. This works easily for family spending on philanthropy (and, less enjoyably, property taxes). The family can plan out the charities it wants to donate to and not worry about arguments afterward.

Still, thinking proactively isn’t what you always want to do, particularly with lifestyle purchases. It may be wiser to consider if you really need that new golf club or pair of shoes that caught your eye.

In these instances, the guide advises employing a technique called “prospective hindsight,” which pushes people to imagine how they would feel if their action turned out positively versus how they would feel if the same act had negative consequences.

“You’re trying to bring the future to the present,” Ms. Allred said. “We tend to be overly optimistic and suffer from confirmation bias,” a term from behavioral economics that means we tend to believe what happens more if it matches a previous belief.

Arguments about spending, particularly within families, are sure to arise. Setting out guidelines on how people in a family can spend money can keep any fallout from devolving into recriminations.