Let's do a thought experiment, inspired a little by some stories in the book "Strangers Drowning" about the difficulties of developing a lifestyle based on altruism.
Let's suppose that a group of altruists decide that they, in particular, due to their special temperament, would like to lead a life dedicated to a belief based on altruism (similar to how, in other times, some people dedicated their lives to communism or Christianity), but they understand that, for them in particular, this type of life would be more bearable if they had a close emotional support network formed by a community of believers; because for them, in particular, assuming economic sacrifices (the more the better, since their altruism would thus be more effective) is unpleasant and inconvenient, and the internal emotional compensations received from the mere act of giving are not enough for them.
Thinking somewhat of "Alcoholics Anonymous", they decide to create with other altruists a kind of group therapy in order to adapt to the new situation of a life dedicated to altruism based on their beliefs.
In the course of this therapy, they discover that altruism might be connected to a lifestyle based on benevolence, of which altruism would be a necessary economic consequence. Benevolence would be a lifestyle that involves complete control of aggression, the cultivation of empathy, and the learning of social skills such as agreeableness, kindness, humility, and rationality, capable of generating trust in others and providing certain affective emotional rewards.
Because they are utilitarians and believe that the important thing is to do "the greatest good for the greatest number," they consider that many people could be motivated to altruistic action not so much by carrying out the altruistic act itself (primarily financial donations) but by leading a lifestyle based on benevolence. Since there doesn't seem to be a contradiction between these two motivations (altruistic action and benevolence), the combination could increase the yield of altruism (that is, the total amount of donations and benefits).
Those particularly interested in benevolence will also consider altruistic action to be the perfect mechanism for channeling a lifestyle based on benevolence (a common mission to share that would test their social skills of benevolence).
It is also possible that other people will join, driven by a third motivation: the old story "of making the world a better place" (there have always been these... but not as many as they say).
Combining these three motivations could yield a greater number of altruistic actions (the greatest good for the greatest number).
The strategies of any therapy group are developed through a process of trial and error (as was the case with AA). Benevolence as a behavioral style can also be approached in ways such as current "assertiveness training" ("benevolence training"). It can also include acting techniques (technically, there is no difference between non-histrionic acting and actual behavior). Nor should we forget the ancient strategies of spiritual exercises that date back to the pre-Christian world. Others will add Eastern techniques, such as yoga or meditation. Various schools or trends could emerge, always aiming for the same goal: altruistic action (benevolence that does not produce altruistic action can never be genuine benevolence).
The development of benevolence can lead to improvements in economic efficiency, as it guarantees mutual trust and the sincere exchange of information and personal sensitivities. The development of benevolent social skills has also the advantage of facilitating coexistence, even in precarious conditions. It could be the case, for example, that believers in altruism might sell their homes, if they own them, in order to get more economic resources for charity, and share less space, similar to how many people live out of necessity in the so-called Third World.
Regardless of whether this lifestyle appeals to a sufficiently effective minority, the community of believers in altruism must consider making itself attractive to the greatest number of people and will therefore incorporate this criterion into its actions: the best way to practice altruism is the one that encourages more people to adopt a lifestyle that involves altruistic action.
My approach is entirely utilitarian: of the three motivations for altruistic action mentioned, only one—the "lifestyle of benevolence"—is a fantasy; the other two already exist, although unfortunately they are not very successful: altruistic giving as a primary life activity and the humanist ambition to "make the world a better place."