Whilst working through Projects 3, 4 and 5 I refered to several of my text books and various on-line videos and tutorials.

For colour choices and mixing:
Marylin Scott, the acrylic artist’s bible, New Burlington Books, London, 2005 – Reprinted 2006.
John Lidzey, Jill Mirza, Nick Harris and Jeremy Galton, Colour Mixing for Artists, New Burlington Books, London, 2002 – Reprinted 2003 & 2004.

For drawing:
Peter Grey, The Complete Guide to Drawing & Illustration, Arcturus Publishing Ltd, London, 2011.
http://www.zentangle.com
http://www.tanglepatterns.com

For printing:
Janet Edmonds, From Print to Stitch, Search Press Ltd, Tunbridge Wells, 2010.

I am currently reading:
Ruth Issett, Glorious Papers, B T Batsford Ltd, London, 2001.

I also watched numerous youtube videos, looked up images and followed links all over the internet increasing my knowledge.

Friends who are very good at printing themselves also kindly offered a few tips and tricks which were very helpful.