Know what kind of fabric you are ironing. Rayon requires a lower setting. If it is cotton - higher, and linen - highest. Iron with a DRY iron. Sprinkle or spray the cloth until slightly damp (with water or starch), or remove from the dryer when damp. Starch can be added at this point. Wrinkles that have dried in the fabric will not come out unless they have been re-dampened! It is also important to iron until the fabric is totally dry. Move the iron slowly over the piece - going quickly doesn't seem to work as well., but too slow will result in scorching.
When ironing pieces with embroidery, use an old towel on the ironing board and place the damp embroidery on the towel - wrong side up. This will give you the best results. The fullness of the embroidery goes into the towel and it is easier to iron the fabric around it.
My favorite starch is Niagara non-aerosol spray starch. It has a nice, light scent and does not flake. I put it in an old fashioned sprinkler bottle to get a heavier application for display purposes.
All the fabrics I dye have been washed and dried many times, and always in hot water and a hot dryer. They will not shrink. However, it is still important to wash light and dark colors separately, as with any of your regular laundry. There are special soaps available if you are extremely concerned about bleeding colors. I have dyed my sheets, clothes, etc., for many years and have never had a problem - everything goes in the wash. Be careful there is no bleach in your detergent, as this will cause damage to the colors.
If you make a garment out of hand dyed fabrics, I recommend it be drycleaned, even though the fabric is washable. Drycleaning will lengthen the life of your garment and keep it looking like new.