I certainly I don't think I'm an expert on the subject, but there is a look that I love, and without trying very hard I can make it work.
Having been asked, on numerous occasions, how I get an old fashioned, antique look to the quilts that I make, I have to say I love the darker, more dramatic colors. When out fabric hunting, it's those that I look for. I'm more of the Old Master's work kind of person. There are stories about impressionistic paintings and how they came about. When the old masters ran out of black, impressionism was born. They started painting lighter and brighter paintings and watercolor quilts are perfect for this.
My special love is working with plaids. When I use them, I'm not fussy about having them straight and on the line of the plaid when I cut them. This makes them have a tendency to be a bit off kilter. I also like working with grayed down colors that have prints of medium or larger size. Never do I work with solid colors, because I like the idea of all those textures you get with prints, plaids, checks and calicos.
Hardly ever buying a tremendous amount of any one fabric makes me run out, and forces me to look for another similar, but different fabric for the quilts I make. After all, Gramma certainly wouldn't have had bolts of fabric to work with. She made do with what she had.
I have a tendency not to have high contrasts going on most of the time, and love the way your eye has to search out what's really happening in the quilt, as opposed to having it all there in the first glance.
I love the old traditional blocks, but hate the inset seams, so make sure to take them out when designing my blocks. It does add extra pieces and seams, but it can be made to look scrappier, and that's what really makes me happy.
I have never over-dyed fabrics to gray them down, as there are so many wonderful fabrics out there, but I do tea-dye muslin for an older, worn look. This picture of Aunt Maggie's Dancin Shoes has muslin which I did tea dye.
Hand quilting is what I think makes the quilt look older. There is nothing wrong with machine quilting, and I have seen some beautiful work. However, I'm about as old fashioned as they come, and prefer hand quilting. I'm not particularly fussy about each stitch being perfect. If it happens it happens, if not, it was suppose to look like that. I like the way an over all quilting pattern looks on my quilts. It adds another dimension to the quilt when finished.
I hope some of these ideas or thoughts on the subject helps you make the quilt you are making, look a little like an antique. Gramma would be proud!