When you are starting a project I 100% believe it is important to have a sketchbook to record all the ideas that you have together in one place, whether they be ideas about composition, visual studies or mark making. This book will then fuel the creation of all your designs when you are moving forward because it is almost impossible to dive straight into producing a perfect pattern without exploring all the available avenues.
For example, this sketch here may not feature in my final design, or even any pattern at all, however the textures in the hair and brush strokes on the skin that I have used whilst drawing it may be utilised in different ways. Abstracting elements from your drawings is a very effective way to create designs with lots of different components. To do this, look through your sketch book and highlight the silhouettes, colours, marks, mediums etc that you would like to develop, then combine together to start testing for your designs. This way you will have used a wide range of information within your patterns, and it would probably not have been possible to do without your sketchbook friend!