The first step to any project is to determine your goals for the project. For example are you looking to get x% of people to read about your event, do you want x# of registrations. Your goals should be measurable so after the project is complete you have concrete examples of the end result.
After the goals are set work backwards to determine how large your target audience is and what response rate you will need from that group in order to reach your lofty goals. Also lay out in general terms what the steps will be to reach the end result.
For example if you planning on sending 3 emails to generate interest in the event, outline what the topic of each email will be. Here is an example:
Email 1: Introduce the event, the date and what the benefit is for the customer to attend, include a link to the event incase someone wants to register immediately
Email 2: Provide an agenda of the event, and bios on the speakers, again include a link so the customer can register
Email 3: Include full event details, push the urgency of the event as it is coming up soon. Do you want to include the option for a registrant to tell a co-worker about the event?
Timing: How far out is the event, what is the timing you want for the emails to go out
Target: What are the characteristics of the people that you intend to market to, who will most likely attend
Other Resources: Is there anyone else that you need to reach out to that can help you write the emails; product experts that you want to include quotes from; Event speakers that you can include a bio.
This is just a general outline of ideas to get you started on writing your project goals and creating the outline so you can stay organized.