You will need a size 2 round watercolour brush. My preference is for a white taklon brush. Any of the following will do, or whatever is available at your local art shop.
Micador For Artists 907 Brush – Taklon, Size 2 FSC 100% : https://micador.com.au/products/Z100502
Jasart White Taklon Round Brushes – Size 2 : https://www.eckersleys.com.au/products/jasart-white-taklon-round-brushes
ROYAL BRUSH Soft-Grip White Taklon Round Brush-Size 2 : https://www.amazon.com/ROYAL-BRUSH-Soft-Grip-Taklon-Brush-Size/dp/B000XZEG2K/
Princeton Snap 9850 Short Handle Round Paintbrush Size 2 : https://www.officeworks.com.au/shop/officeworks/p/princeton-snap-9850-short-handle-round-paintbrush-size-2-ca10687552
You will need 1 or more liquid watercolours. If you are buying only one, I recommend either black, or your favourite colour (the goal is to encourage you to use and enjoy it). If you can only afford 2-3, I recommend pink, blue, and green – you will be able to mix purple and teal from these as well. My all time favourite is Ecoline Liquid Watercolours, but they can be a little tricky to source in some countries. Any of the following will work, or whatever you can find at your local art store.
Talens Ecoline Liquid Water Colour Ink : https://www.eckersleys.com.au/products/talens-ecoline-liquid-water-colour-ink / https://www.officeworks.com.au/shop/officeworks/c/school-art/art-inks/ecoline-inks / https://www.oxlades.com.au/artsupply/ecoline-liquid-watercolour
Hyrdrus Fine Art Watercolour : https://www.docmartins.com/collections/hydrus-fine-art-watercolor
Liquid Watercolor by Artist’s Loft™ : http://www.michaels.com/liquid-watercolor-artists-loft/M10265716.html
When it comes to getting started with watercolour calligraphy, you’re going to want to go through a lot of paper. So I recommend buying something you’re happy to ‘waste’. Don’t buy beautiful, cold-pressed watercolour paper that costs $$ per page! To be totally honest, I do lots of my practice on basic laser printer paper from an office supplies store.
For blending and creating instagram videos, I love a medium-weight multipurpose art paper with a little bit of texture – around 200-250gsm / 135-170lbs such as the following.
Eraldo Field Pad 225gsm : http://riotstores.com.au/item/131610-eraldo-field-pad-225gsm-a5-25-shts.html
Canson 220 Drawing Pad : https://www.eckersleys.com.au/products/canson-220-drawing-pad