How Can I Get Myself To Use More Colours In My Painting?

A great way to break out of the habit of using the same old colours is to try using a limited palette. You can start with four or five fairly 'tame' colours and gradually get more daring. Choose colours that give you a balanced range from dark to light. For instance, you could start with Prussian blue, Titanium white, Venetian red, and yellow ochre. Then paint a still life using only these colours. You will be amazed at the shades that you come up with by mixing colours. As you are feeling more adventurous, try the same exercise but use only Titanium white and several reds that are in a range of tones. The red-toned painting that results will certainly be a departure from your earlier work. Limited palettes can teach you a lot about nuances in colour. After a few exercises, you will likely return to your old palette and use it in a whole new way.

Paint in black and white for a week or so. Then you'll want to use as many colours as you can.