Creases become permanent over time and cause stressed areas. A couple of times a year take the quilt out, give it a good airing, and refold along different lines. Put your quilts someplace cool and dark, out of contact with bugs, pets, and children. Wherever you choose, be sure the quilt is not in direct contact with unfinished wood. This includes cedar chests and closet shelving.
Wood contains acids, and acids are bad for fabric.
Blot up as much as you can and either spot-clean it by hand, or wash the whole thing if it warrants. While newly made quilts can usually stand the washing machine, they should not be dried with a hot dryer. Do not hang a wet quilt from the clothesline, as that can cause the fabric to stretch and stress. Lay it flat on a sheet in a shady area of your lawn, covered with another sheet. If you have to lay the quilt indoors, you can use an electric fan to speed air circulation and drying.