I've found that Bottom Line works well in addition to the advice that others here have given to you. I try to match the applique piece, but if I can't, then I will use a neutral in the same value tone. If you insert your needle just "underneath" the fold where you turn it under..just a thread or so then your stitches will be invisible.

I use silk for needle turn, sts dont show at all. I do have a lot of colors I use but if done right you can use any color you want. I dont do it "right" all the time is why I have a lot of colors of silk thread.

For hand applique I use DMC 50wt.100% cotton thread with a size 11-a needle. I match the colors.

For machine applique I use Connecting Threads 50 wt. I get no lint in the machine.
Hope that helps.

for hand applique - I use silk or aurifil

I am a fairly new quilter and have begun to do some hand applique, which I find very relaxing. I bought quilting thread, which I thought we're supposed to use for hand quilting, but now it sounds like I'm wrong. What do we use quilting thread for?

I just took a class in applique from a shop where the owner does beautiful applique. She highly recomended silk thread. I tried silk and regular thread. I like silk much better it just seems to disappear in to the fabric

I use a single strand of six-ply embroidery thread. It's fine and since I have almost every color in the rainbow from old embroidery projects, it's an easy way to get a color that's a close match for my applique piece.

How many strands did you use?

...if you're right-handed...

I got three sets of BOBs at Superior Threads that are put together for hand applique. The thread is Bottom Line, made for longarm quilting, but it is a VERY fine thread. It's probably comparable to a silk, though I haven't tried that yet. I like it a lot. It is strong and color matching just makes it disappear.

For machine applique I have been using Sulky monofilament on the top and a thread that matches the background on the bobbin. Can hardly see it when I use a tiny zig-zag.