Online Grid Tool
When using the grid tool choose at least 12 x 16 boxes wide; 1 pixel black line style.
Google Search For Charcoal Drawing
Suggested Search Term : ‘B&W portrait / still life / animal photography high resolution’
As you need a high resolution image to print at A4 size, use the following Google Search Tools to refine results:
Go to TOOLS and from the drop down menu underneath, select SIZE and choose ‘Large’ from the dropdown menu.
You can further refine results by clicking on COLOUR and selecting ‘Black & White’, as well as TYPE and ‘photograph’.