I've never gone into my macheing process...
So first, as previously mentioned, I smeared vaseline all over the base. The paste holding all the paper together is glue, after all. Next, I stuck some dry paper around in key places, sticking (poorly) to the vaseline.

-This has two effects; A) it further helps the mache layers I'll apply on top separate from the base when dried - most of this paper will peel off the back while I'm trimming. B) the paper soaks up much of the vaseline, saving me aggravation during the latex coating of the back later.
Next, I pulled on the rattiest old pair of overalls I own.

The paste gets all over my hands, and though I lay a big rag over my lap while I'm working for shielding and hand-wiping, an apron, or work jumper, or this, is called for to save the washing machine a lot of work. -Same goes times 10 for when I'm working with latex; it don't wash out once it's dried, and good luck picking all the specks and drips out of the fabric of your pants and shirts...
So, I started on the edges with pre-cut strips of construction paper.

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I would have started around the outside edges anyway, doubly-necessary because the vaseline strips want to move around, and these strips pin them in place more and more as I add strips that glue them in place.

The single biggest lesson I've learned since I took this up as an adult almost 20 years ago is - the paper needs to lay flat to make good, dense, durable, neat mache. Sometimes you have to let a strip go where it
wants to go, not where you meant for it to - or pull the strip up and try again. You don't want wrinkles or edge-bulges, and sometimes you need to tear a split in the end when you're wrapping around a complex shape, to separate or overlap, depending.
I continue to work in from the edges, covering that first layer...

I'm starting out with construction paper, cut, because I cut up a huge pile of paper years ago, before I figured out torn is completely better except for the work of tearing a lot of paper fairly straight - I have a lot to use up. -Like cut, extra-thick paper doesn't want to lay as smoothly around the edges, so I start with this stuff and finish with thin torn newspaper, which encourages the layers underneath to lay down flat. I'm not just burning off the thick construction paper, either - it strengthens the mask, causing me to spend a little less time putting on more layers for strength.
This is where it was (and is) when I knocked off for lunch (and cat session, and unscheduled helping my little brother trim off a dangerous high-up tree branch - and writing up/posting this much).

I prefer to do a whole mask in one sitting -takes an hour or two- but my mommy was calling, and it does no actual harm to let it sit a while, as long as I don't take so long it dries completely...
More later. It's time to go visit the cats again before I get back to work...