Are you talking about piecing or quilting? for piecing I use a neutral thread like ivory or off white. Gray might work nice since the colors are bright. For quilting - depends on how you are quilting. There are verigated thread in the colors that you are using. Also I use invisible thread on top for SID. It blends in so well that you can not see any top stitches. on the bottom I use thread matchng the backing. Just be careful if you're using dark thread on the bottom and invisible on top that the dark does not show on top.