As seen in the Types of Edits blog, Developmental Edits cover your big picture things.
This is where those Character Profile Templates, World Building Templates, and my Critique Partner Checklist come into play. To snag your copies go to the Writing Resources page.
It's a good idea to wait 2-4 weeks after you finish your first draft to work on edits.
Let's break developmental edits down.
To start, you'll want to do a read through of your draft. I like doing a fast draft read through and this means you're not being nit picky right now. As you read, you'll want to create a new outline, maybe even break it down by chapters, and jot down:
Character Inconsistencies
Plot Holes
Areas that need more/less description
Where you're too 'telling'
Where the pacing is too slow or fast
Where emotion spikes too high for the situation, or not high enough
Did your characters follow their arcs?
Where the plot points impactful and satisfying?
Does it start in the right place?
Does your hook make readers want to read on?
What's great is that when you're finished, you can look at your new outline and see where the holes are, where you need to add or take out scenes. AND you'll basically have your synopsis!
Knowing how to do developmental edits will not only enhance your own writing skill, but will make you a great Critique Partner as well.
It also helps to read your draft like a stranger would. What needs clarification? Would you have DNF'd it? Is your voice there? Is your idea unique? What recent titles could you compare it to?
^This is what an agent is going to look for and want to know, although I've read that some agents don't care about comps as much.
Once I'm done with Developmental Edits, I like to work on Line Edits before moving onto Critique Partners.