The main aim of this tutorial is to guide you through the techniques needed to create an organic feel within your illustrations. Many people try to find an easy way to create images like the one featured here, but to create a genuine colour palette, you'll need to dedicate some time and effort. Try creating watercolour washes manually, scanning them in, collecting images, collecting clip-art (cheesy or not), and acquiring a good in-depth knowledge of Colour Blending and Layer modes in Photoshop and Illustrator.
This tutorial will help you take your illustrations to a new organic level. How far you take it is up to you. Everyone has a style they choose to work in, but blending the organic/analogue with the digital is something that must be mastered and understood. It requires an understanding of your programs and an in-depth appreciation of colour.
Every illustration has an end goal. Every artist has an idea and vision for what their piece should look like. Taking a basic knowledge of traditional fine art and an understanding of digital art and illustration you will start to get the look, feel and aesthetic you have been trying to achieve.
Whether or not you're talented with a paintbrush, the techniques and approaches outlined here will benefit you regardless. Take these tips on board and you will create not only a definitive style, but a pool of resources, too - organic elements that can be used over and over to create a different depth every time.