There seems to be a lot of differing opinions on how to care for fabric. Some people insist on washing every piece, some people say not to do it. Some people say wash some things, but don't wash others. I say, since you are the one using it, do what you think is best!
Today, I will share with you on how I take care of my fabrics for quilting.
Most of my quilting fabrics are 100% cotton, so I will talk about taking care of those, unless otherwise mentioned.
Lets start by talking about washing.
I wash most of my fabrics before using them. I know it gets rid of the stiffness, but it also gets rid of any weird smells and color bleeding. It also pre-shrinks the fabric so the quilt won't warp when one fabric shrinks more than another. This is especially important for flannels. I find that they shrink more than other fabrics.
I do not wash precuts. They will fray easily, and are not worth the trouble.
I use regular laundry detergent and a couple Shout Color Catchers in a gentile cycle, wash and dry.
Once it's dry, I try to pull it out immediately to prevent as many wrinkles as possible. If that is not successful, I will iron the fabric with steam.
I use Best Press starch when I am putting together the quilt and there is small pieces. The starch helps the pieces not stretch and misshapen easily. This is especially true when making half square triangles and sewing on the bias. Otherwise, I generally don't use it.
When I am done, I make sure the fabric is folded nicely.
I usually wash and prep my fabric when I am ready to use it. That way, I know what has been washed, and what hasn't.
I wash the quilts when I am done making the quilt. This helps me evaluate any problem areas and fix them.
I do not wash art quilts, or wall hangings.
Hopefully you find this helpful. Most of my knowledge in this area has come from experience.
Have fun quilting!