If one word could summarize my strategy for avoiding population collapse, it would be “replacement.” We must replace people (zero population growth), replace what we use (consume only as much this year as we consumed last year), and replace resources (for every resource we consume, add at least one new, preferably renewable resource).
Any change in one part of the strategy must be compensated by one or more of the others. For example, if we add people to the population, we must add new resources for them to use. If we increase the consumption rate (resources used annually per capita), we must compensate by adding more resources to maintain the new rate (if we don’t, we will be forced to use the other, unacceptable option: reducing population). If we increase the amount of resources available, we can add population, increase the consumption rate, or both (if the amount of resources will support it).
Every part of this strategy is simple but not easy. To replace people, have on average only one birth per person. To replace consumption, use everything as long as you can; and if you must add something, stop using something else that contains an equivalent amount of resources. To replace resources, find renewable alternatives (consider even borrowing from others); and if they are not available, invest time or money in either exploration or restoration.