"How about using invisible thread if you don't want the wayward stitches to show? I've never used it myself so can't tell you anything about using it."

Because my quilting instructor touted the qualities of invisible thread, I used it on my first quilt top. After several washings and dryings, the heat has melted the thread in many places so that - sometime - I need to re-quilt it. I did SID. Most irritating to say the least. The instructor never mentioned it was unsuitable for a quilt that would be washed/dried often!

STD is the hardest way for me to quilt. If I were a true beginner (not that I'm much past that), I'd cross hatch the whole quilt. Make the lines however far apart is good for your batting. Unroll several colors of thread on the quilt to see what you like. Clear can work. I've not had melting issues as mentioned above. Maybe there are different types of clear thread?

I would do an echo stitch on both sides of each seam.

Beautiful quilt! If you are comfortable with loop-d-loops I think they would look great but I also like the idea of echoing the seams. That would really make the squares pop.

As a newbie to machine quilting I found wavy lines on the diagonal of the quilt to be the easiest method.

This is such a pretty quilt, love the colors! I echo the person who said brown or beige thread. I think it will blend in best and add texture to your beautiful top rather than draw attention away from it. I don't know if you free motion or not, but if you do swirls would look lovely on this. :)

I agree that a plain crosshatch pattern will work fine - personally, I would do them about 2 inches apart. Have done that several times on similar style quilts and really liked the way they came out. Stitch in the ditch is not easy to do well.

I would do an all over FMQ meander or large stipple. Or a Rose meander. I love variegated thread.

I also vote for loops. I am relatively new at machine quilting as well and for some reason have been better at loops/swirls than crosshatch and lines because I'm such a stickler for perfection on the lines. With loops and swirls, they are better if they are not perfect.

Do you mind sharing what fabric collection you used or did you just choose a variety of different fabrics and coordinate them yourself? Beautiful!

I don't like quilt in the ditch as I am unable to stay in the ditch. I have found that by doing a gentle curve from corner to corner all around a block makes a good look and I do it with the walking foot.