I just got done reading on a popular forum that you should not waste your time writing any sort of plan. And you should just get to work and do something.
While I may read into that a little more than the author meant, I will agree that to a point he is partially correct. What he should have said is not "don't make a plan" but instead it should have said do not spend too much time making a plan and miss out on opportunities do to over analysis.
When putting a plan together consider your outcomes, that is the basis of a plan anyways... If your outcome is a couple hundred dollars, do not spend all day on it. If its a few million dollars, then I would expect you to spend some time on the subject.
Now where we get into the plan. As with all my plans I write, I start with an outline and as I write an outline I generally start at the beginning and end (outcome) then work towards the middle.
In most simple terms, your plan is nothing more than a checklist at this point.
Now, that you have your basic plan in place, is it time to get to work or is this a time to develop that plan into more doable chunks. Since, for this posts sake, we need to develop the plan a bit more we begin by filling in the outline. Each step may need an outline for it. Then later it may need more development.
For my marketing plans I generally start with social media as that is the "hipster" way to market things. Its also a very cost effective way to Market your products or services.
I have an outline that I reference for all my projects specifically for social media. I start with it and decide what marketing platforms work best for my project. I then develop that outline into a basic guide for all my marketing efforts.
As your plan develops, it will change but you now have an outline in place to achieve your end goal.
Get to work, make some $$ but in the meantime work on your plan as well. You will never get to the end of the forest if you do not have a map to get there.
If you would like a copy of my Marketing plan outline, check out my gig on fiverr.com.