There are 5 steps to manage constraints are:
1) Identify the constrained resource
2) Decide how to make the bottleneck as efficient as possible
3) Make the exploitation of the constraint the top priority and all other decisions secondary.
4) If more capacity is still needed, add capacity via capital investment, outsourcing, process redesigns or other means.
5) Return to Step 1 and find the next constraint.
Which one is the most difficult and why?