Blackwork is commonly a counted stitch embroidery which is usually done on an even weave fabric, using black thread on white fabric. Scarletwork and goldwork are the same method in red or gold thread. It is used to decorate cuffs and collars of shirts as well as many other garments.
Below is an example of double running or Holbein stitch. It will create a smooth even line. You want to make your running stitch as long as possible so that you will have very few ends to work back in.
Often my blackwork looks a mess on the back, just knots and loose threads everywhere, unless it is a gift or a piece to show. They say that cobblers kids never have the best shoes, I think that goes for tailors too. I find it difficult to find time to get my own garments up to the standard that I make for others. I will talk more about blackwork in the future.