First of all,
for supporting my "design" habit and thanks!
I've found that a contrasting color from your project yarn is a must. And it MUST be smooth and colorfast....so I use a 5/2 weight (WEBS carries it) or a single strand of embroidery floss works perfectly. 5/2 is a tad bigger and twisted but embroidery floss is quite strong. Another suggestion is Quilting thread....VERY strong and super easy to find in sewing shops or departments.
Before I started using the interchangable needles, I'd thread a blunt needle with my lifeline and just below the circular needle filled with my project, starting at the round marker, go through each stitch all the way around, then, stretch out the project as much as possible or leave extra lifeline and knot, reknot and knot again. once you've passed that lifeline and are sure you're on your way and have placed a second one, remove the first one. Unless you're completely confident...place one at least once every 10 rounds and always on a knit round. Knit rounds are much easier to pick up if you have to rip out. And lifelines save major tinking. Hope this helps.....