The marker has two ends, one end is a small nib, one end is a large nib, there is nothing to say about the small nib, and the large nib needs to be used with some techniques, such as lining up the lines, to draw the lines by putting the inclined side flat against the paper.
You can also stand the nib up slightly to draw a thinner line, or stand it up while drawing to draw a gradual line from large to small.
In addition to lining up lines, markers can also be painted flat. When painting flat, you need to repeatedly erase until you get the color even, because markers are translucent and have covering properties.
You can draw a box and practice these three exercises in the box, these are the most basic skills of using markers.