You can use any color thread you like. I am working on a project now and am using variegated thread that goes from deep yellow to white in subtle graduations. The quilt is predominently black.
I prefer to hand quilt with a heavier thread (35 weight). With thread the lower number signifies a thicker thread so 50 weight is finer than 35 weight. I actually break the rule and on average I use a length of thread that is longer than my arm. When I spin it off the spool I go the entire length of my arm and across my torso so I am probably using a length about 30". I use beeswax (DH keeps bees so I have a good supply of capping wax which is the best quality and smells so good!) A little wax goes a long way. I also make sure I move the thread regularly so it doesn't fray and break at the eye of the needle. I never have problems with knotting or tangling. I attribute that to the wax and using a heavier thread. If I forget to regularly slide the needle down the length (I do it every other needle full) I have had my thread fray and break right where it was in the eye.

This is because of the way the thread is wound. If you thread it from the other end, you'll find your thread will tangle and twist something horrible. Every once in awhile I do this and I always know almost right away what the problem is. Not always, but most of the time. There's always that one time when I scratch my head, growl at my thread, and wonder what the heck is wrong. Obviously it is operator error. :oops:

I hand quilt- I always use hand quilting thread. I've used all white, all ecru, and on a broken star with black backgrounds, used a varigated thread to do the quilting. It looked fabulous. I wax the thread also or I end up with frayed thread. It slides easier through the fabric.
I don't believe there are any "rules" with the colors you use, just like there are no "rules" for designing your quilt.
Have fun.

I hand quilt and I use what ever color thread that looks good on the quilt. I even use several different colors on each quilt if that is what it takes to make the quilt look that way I want it to. I am the designer so I make the rules.

I saw on tv just the other day that when you hand quilt, your needles should be the same length as the distance between the end of your forefinger and the first joint. My length is 1 1/4" -- now I know why I like longer needles.... :D

I guess that's why I love a 12 :shock: My aunt said she didn't know they made needles that small :lol: :lol:

I usually use ecru dual duty quilting thread by coats and clark. Occasionally, I will use a color. For example on this quilt I am using a dark pink. I didn't want the ecru to stand out so much on the black and the Pink is really dark so won't be a noticeable. But I usually go for an ecru.

If you don't like the contrast of the white and ecru on some of your darker fabrics, believe it or not gray/grey works great and blends beautifully even on the back. I was shocked myself.

I use one color.

Grey thread is amazing because of how well it disappears against other colors. I use either ecru or grey thread when piecing for exactly this reason. I would have never believed it when I first was told this but it has proven true and I am a firm believer in using grey when I don't want the thread to show up.