Take a photo of your still life and open it in Photoshop, turn into grey scale and add a transparent colour layer. Try to make an assortment of digital monochrome colour studies, which will aid when making your monochrome painting.
If you are unfamiliar with using Photoshop here are a few steps to help you get started.
Step 1: Photograph your still life and open the file in Photoshop. Below is a work by contemporary artist, Till Rabus, which I will use for the tutorial.
Step 2: In the title bar, under image, select mode and greyscale.
Step 3: Then once your image is in greyscale, switch the mode back to RGB.
Step 4: Select a colour from the colour picker, then select the rectangle shape from the toolbar, which will be dragged over the image.
Step 5: Using the opacity slider, which is located in layers tab, slide it to alter the transparency of the coloured rectangle over the image.
Tip: If you do not see the layers tab, open the Window drop down menu and check the Layers option. Window is located in the top menu bar between View and Help. Most option can be made visible under the Window menu, have look.
Step 6: In the top menu under Layer, select flatten image.
Step 7: Save File as a .jpg.
Try exploring a different colour transparencies, which will help as you decide on the monochrome colour scheme you wish to develop into a painting. Use your digital studies along side with your still life as the objects in your still life should still be observed – Actual objects will offer a higher degree of visual information.
Other colour examples:
Contemporary Still Life Examples: