how do you chose a thread color when starting a quilt? I have a very small print in navy blue and white that I want to quilt. There are solid white blocks in the pattern Ive chose also. White is most dominent color in the background.

When deciding what color I want to use, I will pull the thread off the spool a bit and then lay it down onto the quilt to see how it will look.

me too, enough to puddle, then move it to different sections to see which color looks best on the most places

would I have to use two different colors in the same quilt? I am planning to use a stencil design in the solid white blocks and an overall design for the blue/white print areas. This quilt pattern is sometimes called a Crown of Thorns or Georgetown Circle. Its squares and triangles in the print block with solid white blocks in between. I am handquilting the quilt.

I use white or off white for all my hand quilting - even on dark colored blocks. After it is washed and gets a little puffy and wrinkled, it just blends in. You can do the 2 colors, though. Like it was suggested try it out and see what you like.

I am still learning to keep small stitches so on that thought I may well use the white thread..lol at least it would blend in better till I get better stitching..:)

Are you referring to the piecing or the quilting?
I've taken to using light gray, dark gray, black or white for piecing.
For quilting I just meander so I pick a color that won't show.

I've seen hand quilting done with contrasting thread in order for it to be seen.

I used to be real 'matchy matchy' when it came to quilting thread color. Now I pick something you can see on every fabric. The purple quilt on the frame is being quilted in a soft green.