Pin marks can be minimised by leaving the pins high - not pushed down hard - and letting the dye flow under them, or by using stenter pins.

A better way is to include a border in the scarf design. Remember that interrupting the border line makes the scarf much more interesting. Either lay down the gutta or wax line to define the border at the beginning or after all the other painting if you want to avoid white lines.

Paint the border last. When you are ready to do this take out alternate pins. Mix plenty of dye and use a large brush. Take out a corner pin and paint this part of the border, supporting it with your spare hand and run the brush under the hem. Replace the pin. Paint the border from this corner, going in each direction alternately so that there are no wet on dry tidemarks. Take the pins out and replace them as you go, running the brush under the hem.

Your hands will be colourful but the silk will be pristine.
PS. You may like to change the border colour as you go, adding a few drops of another colour as you progress. The border is the most visible part of a scarf when it is worn and a variable one looks good.