I try to keep my mind as empty as possible of non relevant processes, that's why I use a task manager to handle my tasks and meetings. This system has a side effect, if there isn't something reminding you that you have to do something, you fail to do it. That principle applied to human relationships means that if you don't stumble that person in your daily life, it doesn't exist for you and you will probably not take enough care that the person deserves.
To solve that problem I started creating periodic tasks to call these people or hang out. I've also used those tasks to keep a diary of the interactions.
Recently I've found Monica a popular open source personal CRM that helps in the same direction.
So I'm going to migrate all my information to the system and see how it goes.