Well, you could start by purchasing just an ordinary black pen with a fibre tip. These are stocked in all stationers, art shops etc, they are very cheap, but they will do the job. They are so easy to carry around and will achieve many different strokes. Depending, of course, on how much pressure you apply to the nib itself. As for subject choice to draw, probably something small to start with. Leaves are good for the detail, eggs, pebbles or stones from the garden or beach, even shells. Anything like this would do nicely. try this out
Now you need to create a form and lay a texture. What do we mean by this? You can lay a few dots, lines, dashes, all with more or less pressure giving a rough outline. For example, with your marks close together it will appear darker in intensity. If you want it really dark you can Cross Hatch. What is Cross Hatching? This is when you draw a set of lines, then do another set of lines across them, going the other way. This will give you very dark areas. You can also obtain a rounded effect by making it darker on any dip of a curve of any sort and then lighter as it comes out of the curve itself.
How about adding a wash to your work! Pen and Wash, you will find, works well on quite a few types of paper. Pens are okay on smooth or shiny surface paper. Washes look good on heavier grained papers. So, now you have done your sketching with your pen, now for paints. Block watercolour paints are ideal diluted with water. Keep your wash thin, otherwise you may block the lines of your drawing. Remember the light will reflect from the white paper.
Some people use water soluble pens for the original line drawing so it will seep into the wash. As for paints, if you use block paints, these will slot into your palette. This is sensible as you can always replace them. These palettes are ideal as you can also mix your paint on them, have them at your side, enabling you to work quickly. Washes are not needed to be particularly accurate. When one colour runs into another, it can often add to the effect and become an advantage. Mistakes with pen and ink are a bit of a problem. It does not work to put more layers of paint on, as the paint itself, you could say, is translucent. You can sometimes amend your work with a grainy ink rubber, but do wait until your paint is dry. Do not be heavy handed or it will take away the surface and mess the ink and paint up. So remember, a light touch is needed with the rubber. Leave some white, unpainted, areas on your work to give a bit of contrast!