I like the results from coffee rather than from tea, but I do both, I just save up all my old tea bags keeping them in the freezer, when I have enough I put them in a bucket of hot water, when I have a nice strong brew I put in fabric which has been washed and wet through,(do not put in dry fabric to the dye bath, this will result uneven patches) I give it all a good stir for a while and leave to soak over night, but a few hours is ok to. Rinse with 1/2 cup of white vinegar and a Tbl spoon of baking soda to set the dye, rinse till water runs clear. If a darker shade is required just keep repeating the process. I do this a lot to unify my small florals etc since I mostly use scraps and recycled fabrics this method helps to give a good allover design and is great for knocking back those colors which are too bright. Works best on 100% cotton fabrics and those which have white or pale colored threads, does not work so well on darker solid colours. It is great to experiment so try out on some scraps first!
Gal