Transferring Work from Needles to Yarn

I’m still working on the never-ending minisweater.

I’ve finally knitted enough so that I can now transfer the work onto an extra piece of yarn, from the needles, so I can knit the body and sleeves separately.

Thing is, I’m not sure how to go about doing that without having everything fall apart. Should I slide the needles out and just be really careful? Should I do it stitch by stitch? Should I get a smaller tapestry needle and thread it all through, THEN remove the needles?

I am so scared, haha.