Just read your original post to start this thread.
When I was in my 20's we had a pond cleaned out. Not knowing any better I let them spread the mud all around and it killed a bunch of big oak trees.
I cut one down and went to work making firewood for myself with a worn out chainsaw, a 8# sledge and wedges and a "monster maul". That got old real quick so I did some pricing of a powered splitter and a new saw, and some calculating of what the break even point on cords of wood sold was.
Long story short, bought new saw and splitter and sold enough wood the first 2 years to pay for them both.
Still have the splittter and would probably have the saw too except someone stole it.
Look into a used splitter at a minimum if you want to sell at multiple places and be able to keep them stocked.
Selling by the bundle or stack is the way to get the most. I figured up one time what the difference in selling a cord vs selling by the stack and you get more than 2x the money
Also unless you are marketing kindling, split into pieces that you can easily handle with one hand and move on to the next bundle. Don't waste time and energey making splinters

Figure out about how much you can produce and how much each location sells. If you can't keep a supply of wood they might have someone else come along and take over your location.
Sell the excess by your drive or set up on Saturdays at variuos spots and sell out of the truck
Have enough ready to sell to cover 75% of your expected demand for the season before people start thinking about building fires
That is my .02, I.m sure there is a lot of good advise in the previous posts as well