It is a longstanding Catholic custom to provide money to religious orders or parishes for Masses to be said for the repose of one’s soul. If you would like to take advantage of that custom, you could start setting aside money for that purpose. (The usual stipend is approximately $10 per Mass.)
I recommend that you have a will drawn up with specific instructions that the money you’ve set aside for the Masses is to be disbursed only to the religious order or parish you’ve designated for the express purpose of offering Masses for the repose of your soul. Whether or not your designated executor personally wishes to have Masses said for you, he or she will be legally required to follow the terms of your will.
Your profile indicates that you are Protestant, so if you wish this to be done, it will be especially important for you to draw up a will specifying it. Should you ever choose to become Catholic, you might also wish to discern a vocation to a third order attached to a religious order. Religious orders always include lay members of their third orders in the prayers for deceased members of their order.
