A plan that starts with your mission, vision, values, goals, strengths, weaknesses, marketing strategy, budget and sales projections can take weeks, if not months, to prepare. Such a plan, however, is useless without a plan to implement it.
An effective implementation plan defines each category of activity (ex., your website), specific actions that need to occur inside that category (ex., add white paper for download in exchange for visitors' names and contact info), a coordinating date due (ex., quarterly) and the individual responsible for implementation (ex., Rex, website manager). Without this accountability, implementation of your plan will be sporadic and ill-defined. In other words, a marketing plan amounts to little without accompanying marching orders.