I do alot of applique, mostly hand needleturn, but when I do a machine applique and want to be able to wash it this is how I do it.

I use the monofiliment thread and stitch close to the edge as possible with a very narrow zig-zag, then accent it with blanket stitch. By using the mono thread, you don't see the stitching and it secures the edge well enough to keep the fraying to a minimum.

As for color, it depends on the effect I want, but I do use alot of the variegated threads, like the look.

I usually pick the background color, except inside the applique, where I try to get something that blends in with most of it. Applique most of the time is supposed to look old fashioned, or at least that's what I tell myself when I can see the threads too well, and can't find the horse to ride at a gallop past the quilt.

Thanks to everyone that gave me such good answers, you were very helpful.
=^..^= meow

Same here.