The most important factor is always to have clean hands. If the embroidery does not get dirty then you will not have to wash it. Washing embroideries can take the luster out of the stitches.
When framing up the fabric in the beginning, also frame a piece of white acid free tissue paper with the fabric. Place the tissue paper over the fabric, put the two together on the frame. When the fabric has been framed you can cut away a window in the tissue paper (where the design is), and the surrounding tissue will protect the fabric underneath from getting dirty. The tissue paper needs to be acid free because if the embroidery is left for a long time, the acid from ordinary tissue paper can soak into the fabric and will eventually turn the fabric brown and rot it.
Old sheets ripped into pieces make good dust covers and can be pinned into the frame with the embroidery on the stretcher bar frames, scroll bars and slate frames.
Food and Drink
I know it is obvious, but it is so tempting to have a cup of coffee or even water next to your embroidery for a quick sip. Unfortunately when a spill happens it can ruin not just the embroidery but your whole week. All the time and effort spent should not be wasted from one silly mistake. I now never have food or drink near by while doing my embroidery as spitting food on your work is not a mistake you want to make, I know!
Be safe rather than sorry. Keep all food and drink far away from your work and wash your hands whenever you have left your embroidery and come back to it. There may be greasy stains left on the last object you touched by happy fed children or husbands that can be transferred onto your work area.
If you get blood on your work, immediately take a length of sewing thread (e.g. polyester thread), roll it into a ball and pop it in your mouth wetting it with your own saliva, it should be wet but not dripping. Put a piece of kitchen towel, tissue or piece of white cloth under the embroidery to act as a blotter then rub the wet ball of thread over the blood spot, you may have to repeat this a couple of times. The enzymes in your saliva react with your own blood and dissolves it. This process needs to be done before the blood drys for it to be totally successful.
Occasionally a water mark may be left depending on the type of fabric you are working on. It is difficult to remove a water mark if one is left, even after washing the mark can remain, but more than likely you will be lucky enough not to have a water mark. A water mark is also less noticeable than a blood stain.
Try to avoid washing your embroidery as this could cause damage to your work.
Instances: If the fabric that the embroidery is being worked on is not prewashed then that fabric could shrink and the embroidery stitches stay the same, leaving the background fabric puckered. Also if the fabric is a died fabric i.e. a red silk, the dye can run into the embroidery stitches.
Washing a piece of embroidery can take the luster out of the embroidery stitches leaving the stitches dull or worn looking.
If washing is very necessary: Prepare a bowl with luke warm water and well diluted mild soap suds. Submerge the embroidery in the water, agitating it gently but not screwing the embroidery into a ball as this will cause wrinkles which can be hard to remove.
When the embroidery looks clean, remove the embroidery gently and rinse the embroidery clean of all soap. Lay the embroidery out flat on a clean white towel which will absorb some of the water and allow to dry.
If there are wrinkles in the embroidery when it has dried then place the embroidery onto a soft white clean towel with the right side of the embroidery against the towel. Place a piece of tissue paper on the wrong side of the embroidery which is facing out. Choose the iron setting appropriate for the fabric and threads of the embroidery, if you are not sure set the iron on a low heat to start with and increase the heat gradually if necessary.
Gently iron the embroidery with the tissue paper between the iron and the embroidery. The tissue paper acts as extra protection incase the iron is to hot and burns the fabric or if there is a residue on the bottom of the iron that accidentally gets transferred onto the embroidery.
If wrinkles remain in the fabric, they will likely be removed when mounting the embroidery on a piece of acid free board ready to go into a frame.