Here's the non-technical part of what I learned. I hope some fraction of this is useful to you. These are the fundamental things that cause people to pay you money to do your work. Others can advise far better about the technical and logistic levels of detail.
You need to get the customer (who is paying you to do marketing) to specify what message they actually want to deliver, what 3 things they want the customer to walk away knowing. Everything else reinforces those 3 things. You also need to know who that customer is, and how they have traditionally reached them. It would help to know what the customers needs are as well.
The customer's boss needs to know their marketing budget isn't being wasted. You need to figure out some criteria they will agree to, as a measure of success. This means you need to be able to measure how many responses they get through the sales channel, etc. In the Trade-Show business, we were able to have people actually fill out paper surveys, and tabulate those. The world has changed, but the ideas are the same.
Read up on A/B testing, etc... this isn't something we really did, it's more of a computer enabled tech.