Not all of these may not apply to what you're marketing, but the core elements remain integral.
The first step is to formulate a media plan. The purpose of media planning is to conceive, analyze, and select channels of communication that will direct advertising messages to the right people, in the right place, at the right time.
Media planning should consist of a Marketing Plan and an Advertising Plan.
The Marketing Plan should consist of marketing objectives, marketing strategy and marketing tactics.
The Advertising Plan should consist of media objectives, media strategy and selecting media. Part of the media plan is to select media vehicles, particular magazines, or broadcast programs according to how well they deliver or expose the message to the desired target audience. In order for this strategy to be effective it must have continuity. It must have a continuous schedule where it seeks a set level of exposure during the entire campaign. It must also utilize Reach and Frequency.
Reach is the total number of different people exposed at least once to an ad in a given time period. Frequency is the number of times the same person is exposed to an ad in a given time period.
A successful advertising campaign should identify a target audience, the product the communications media and the advertising message. You must understand and agree to these four elements of the advertising strategy before any creative work begins.
Without the proper marketing strategy you face fragmentation of your message.
For a proper situation analysis it must identify the brand. It must identify the industry which includes the competition. It must identify the target segmentation, (the demographic and what they desire, what drives them behaviorally). It must also identify the key products and benefits of the brand which includes the brand advantages and differentiation. Finally it must identify the single most important message to communicate.
I write this not as a layman observer, but as someone who as part of my degree in Mass Communication has studied Public Relations and Advertising, Principles of Advertising and Advertising Campaigns where we developed an integrated marketing plan for an existing company.