Conducting a large-scale assault

So, the tortuous first stage is passed. Now all I have to do is obsess over whether I should have said "tortuous" or "tortured", and check it is meant to be "passed", not "past", although I think technically both are true. (And I want to be a writer. I'll try to learn basic English soon.) Now I'm on to Step Two, the one I've been looking forward to: Editing.

But where do you start?

Seriously. I'm asking anyone. Where do you start editing a novel?

Don't say "at the beginning". I'm not talking about fixing sentences — I'm talking about a proper edit — rewriting a good chunk of the novel.

I figured I'd start with structure. I want to begin with a different scene (much more interesting than its current bland introduction), move a few scenes around, make some scenes into flashbacks for later on.

But how do I even change the structure? Do I make index cards of each scene and decide which order they go best in? Copy/paste scenes? Refer to a "novel outline" ("First 5000 words: Introduce protagonist. Next 2000 words: Catalyst event", etc) and organise it that way?

There are so many courses and books on how to write. So many helpful websites and blogs on how to sell and market your book. But where's the information on how to do a large-scale edit?

I feel I should know this. I am the writer. I've edited lots of short stories — done big structural changes, rewrites, you name it — but they were short stories. They're a whole different level of writing.

I think the approach I'll go with is the index card one. Write out a one-sentence summary of each scene, and figure out which should go where in the narrative. Conduct large-scale assault on every scene in my poor little first draft. Everything that can go, must go! (Sale on now.)

Does anyone have any other ideas?