Very difficult undertaking indeed. There are so many things to get right. Choice of colour and size of the pattern and how many times you want it to repeat are crucial decisions. You have to get this right early or it will never look
quite right.
Dom is spot on again. Practice the pattern before committing yourself. That way you'll learn what your strengths and weaknesses are and if the thing is doable in the first place.
I would recommend first couple of goes on primed up plastic sheet. That way you get the feel of the pattern and how it makes your brushes behave. I say this as paper will be different. Then if you reckon you have the hang of it, practice
again on an old piece of rubbish dead figure you have languishing in a cupboard
(we all have them). That way you get to see how your brushes and paint behaves on a '3D' contoured surface - which will be different again.
If you've seen my mediocre efforts in the past, you'll notice I'm not one for doing repeating patterns. Another difficulty is making things uniform, at at least
appear uniform.
Good luck, I know it is a long answer, but what you propose isn't easy. I hope I haven't put you off.
All the best