no plan survives contact with the enemy

be one's own worst enemy

To act contrary to one's own interests; to cause problems for oneself; to self-sabotage.

game plan

Any strategy devised to reach a given objective.

let the perfect be the enemy of the good

To insist on the total realization of a goal and reject any compromise, thereby decreasing the chance of achieving even a part of that goal.

master plan

A comprehensive document that sets out an overall strategy; the strategy itself.

sounds like a plan

Used to indicate agreement with a proposed suggestion.