There are many "calligraphy" pens available to buy, but you want to look out for flexible tipped pens rather than fixed width pens. Whether you choose the large tip or a small tip is just a matter of personal preference and the look of end result.
Large tip pens
KARIN BRUSHMARKER PRO
Very soft brush tip markers filled with water based ink.The tips are made of durable nylon fibres that give them their flexible tip. They have beautiful saturated colours as well as metallics and neons.
ABT TOMBOW DUAL BRUSH PEN
ABT Dual Brush Pens have two tips - a versatile and flexible soft brush-shaped tip for fine, medium and bold strokes and a fine tip for more precise lines, borders, graphics and stencils.
Available in 107 water-based colours plus bender.
ECOLINE BRUSH PEN
Ecoline Brush Pens are filled with Ecoline Liquid Watercolour Ink and are currently available in 57 colours plus one colourless blender. The inks are transparent dye based and not lightfast.
CRAYOLA BROADLINE WASHABLE MARKERS
These Crayola pens are not technically brush pens, but with a bit of practice they can be used to emulate the look of a large brush pen. The ink is washable and the upside is that they are cheap as chips!
Small tip pens
TOMBOW FUDENOSUKE SMALL TIP BRUSH PENS
The Fudenosuke brush pen is one of the best on the market. There are two tips to choose from - soft and hard. The hard tip is slightly easier for beginners to use and the soft one gives better contrast between the thick and thin strokes. But get one of each and make your own mind up.
PENTEL BRUSH TOUCH PEN
These pens are my personal favourites for small brush pens. They have a soft flexible fibre tip which gives good thick and thin calligraphy strokes. They come in a range of great colours in non permanent water-based ink.
ZEBRA FUDE BRUSH
Another great pen. These come in either thick, medium and extra fine nibs. Similar to the Pentel Touch above, but the thick is much thicker.
ZEBRA BRUSH PEN
Zebra also do coloured small tip brush pens. These are just great for experimenting with colour lettering. Acid free archival quality ink that won't fade.
When doing calligraphy with brush pens you need the smoothest paper you can find. Too rough a texture and the paper will fray the tip of your pen and make it look a bit fuzzy. The paper can be plain, with lines, squares or even dots, the choice is yours. Listed below are some of my go to paper pads which are relatively inexpensive and have a really smooth texture.
If you are printing my workbook or the guidelines to use them to write directly onto, choose a printer paper that is at least 120gsm. HP do nice heavy papers, but are by no means the only ones available. Test your pens on the paper to see if they bleed - if they do walk away!
Rhodia paper is one of the best. The pads come in plenty of 'A' sizes and have either plain, dots, squares or lines. They are super smooth and great for practice.
MARKER or LAYOUT PAPER
Marker paper or Layout paper is thin enough to see through to what's underneath, but isn't as translucent as tracing paper or velum. Plus it is designed to be used with marker pens so it shouldn't bleed through.
Tracing paper is perfect for practicing your basic strokes, words and layouts. Translucent, smooth and bleed proof its a really useful tool. You don't have to buy Goldline as there are many manufacturers of tracing paper all of which are just fine.