You'll note that I'm totally organized at all times.
It may just be easier to tell you what not to do with recycled sweaters. This is in no particular order, believe me.
Purchase sweaters that are no more than 30% of who knows what that is added to the wool. Try, try, try to have the same thickness sweaters. Not too thick, not too thin. (And that's right out of Goldilocks and the Three Bears).
Check out Kat Wise on Etsy (just Google) for some delicious, over-the-top sweaters coats. I did buy her tutorial and love it.
Your main concern, whatever style you choose, is the bodice. It's what holds everything together. So choose wisely, something that fits you even after washing. And by washing, it kinda needs to be felted, but comfortably and not a piece of cardboard.
I'm about 3/4 of the way done 'cause I need to show you something at our meeting. Honestly, I've never done anything remotely close to this and I know we have some extremely talented members so this should be a cake walk for you.
Always keep a spare Barbie doll close at hand for those sweater you washed once too often and I wil give you more "avoid disaster" tips at our meeting, plus as I mentioned, I'm bringing sweaters that I've washed and dried and will sell them for what I paid for them. I guess I got a little carried away