Why do I design my linocuts in blue?
The main reason is, I just find it works for me!
I'm sure others may have their own preferences.
It seems easier for me to mix a consistent range of blue tones. Think of those tricky greenish tones you can wander in to when you darken yellows, reds go to pink when you lighten them! Then I find blue easier to keep the different tones separate in my mind, when I am working through the various layers of a reduction print. They also seem to scan fairly well, although they rarely print out true (maybe my computer/scanner/printer needs some adjusting or calibrating? )
Not everyone works in a stepped tonal way when making reduction linocuts. I nearly always print from lightest tones and finish with the darkest. The most layers I have ever cut and printed for a single design has been six.
I don't permanently mark the block with the design. After each round of cutting I use a graphite paper to transfer the next layer of cutting and printing to the lino. This makes the registration of the design onto the surface of the lino very important. I used to just line up the edges and use masking tape to fix it into place. However, a few of my linocuts have quite complicated edges, so I've now found a method of lining up the image each time by using a fine drill to go through the design and the lino in several places. If you then put a few drill bits into the holes in the lino the holes in the design can be slotted over the top and everything lines up perfectly. It is more complicated to explain than do (promise)!
Because there are several layers of overprinting for each design, registration during printing is very important as well. I usually mount the lino now onto 6mm MDF. this then fits into a frame, also made out of MDF and card that allows me to place the (very expensive) paper in to what is hopefully exactly the same place each time. This system is cheap as the frames can be used many times and I have found it more accurate than the pins system that is sold (others may disagree).