For warming up I started drawing different details from berries (top right). You can also see my painting studies on the right side:

 

I started with blueberries because they are relatively easy to paint and explore. I painted them in watercolor with details in acrylic ink:

 

The strawberries were painted with watercolor (leaves) and liquid watercolor (red parts), which is very intense and needs to be toned down a bit sometimes:

 

The raspberries are a combination of watercolor (leaves and berries), and liquid watercolor in saffron yellow on top - I love the warmth it gave the illustration: