Start laying out the pieces on the floor or a large table. Have fun with this; you can't go wrong as long as you picked colors that compliment each other. I like to do a rough size layout first and then re-arrange and tweak it. I think the last one I made was 60x80in. Also, on this one, I turned the pieces so that the sleeve cuffs and bottoms of the sweaters for the outer edges of the blanket

When I'm ready to sew it, I pin the whole thing together. Then I either pick up a section at a time and sew it or just pick up the whole thing and sew it all at once. There are advantages to both methods, I've only made three of these so I'm not sure which method seems faster or easier

I'm sewing it together with a conventional zig-zag stitch, the widest setting and a med/small length (3.5 on my machine). There is not seam allowance, it's just what I call a "butt-joint", joining the two raw edges together flat and zig-zagging across them

Here's the finished product, throw #3. I had wanted to use some reds in it, but they just didn't look right, so I put one tiny red square in the middle for whimsy. I also left some of the sweater details, such as buttons on a cuff, or embroidered flowers on the hem. Varying textures (cable-knit, rib-knit, etc.) and details like the buttons are what make the throws unique.