This is a vital question and from my own experience, I have come to realize that, there is an expectation of what the client wants to see in your proposal to be convinced the campaign will be a profitable venture; Here is my winning approach; I focus of getting the follow aspect right.

1. Consumer Analysis - I show the client I understand the consumers enough, and know the right things to say to capture their attention. the client knows a lot about his business and its environment but not much about consumer behavior, and what insight to speak to that will trigger purchases or the desired action.

2. Clearly defined Engagement Approach: Consumer engament must be strategic, so client expect to be convinced you have the right communication approach.
In my own case depending on the stage of consumer engagement requirement, but I deploy the approach of - REACH , ENGAGE, CONVERT, AND RETAIN. I wish I have enough room to explain this better. Just make the client see how you intent to reach to create awareness, engage to build trust, convert to grow sales, and retain to drive word-of-mouth referrals, and advocacy.

3. Execution Plan: Now that the client know your engagement approach, show him how you intent to use the various digital channels to achieve the communication goals, and set KPIs to track results.

- Show how you intend to use SEO to create awareness and drive traffic to website or landing page.
- Show how you intent to use Content marketing to build trust, and generate leads.
- Show how you intend to use social media to build an engaged community that will trust the brand, and how you will use social media to persuade consumers to make purchases.
- Show how you intent to use other digital marketing strategies to encourage repetitive purchase , customer loyalty, and brand referrals.

Just let them see how other channels not mention can be applied to accomplish the communication objectives set out in your engagement approach.

What not to Include or to include;

Don't forget to have a communication theme or big idea, and the campaign core message included if the client did not already have a campaign message.

Remember to put a timeline to every stage of your engagement approach (REACH, ENGAGE, CONVERT, RETAIN) this can also run concurrently.

Do not include budget in your presentation slide, just focus on getting the client's buy-in, his body language and question will tell you if he is a high paying or low paying client, don't also forget that he might not run with the whole idea at the same time, so brake the budget into deliverable timelines, and make it easy for him to start small and go big as you achieve set out communication result.

I hope this help.