Do not start with knots; leave thread tail when you start and then hide them inside stitches, weaving them into the stitches on the backside; this way you will have less of a mess on the back. Same way when you end the stitches, hide the extra thread tail inside stitches and cut it off carefully. If you have seen the work of Trish Burr she specialises in embroidery that looks the same on front and back – needle painting.

Some stitches are reversible – like holbein stitch of black work, sashiko. They look the same on the front and back. I hope this is what you are asking.

There are also self-adhesive fabrics available that can be cut to size and stuck to the back of the embroidery.