I think a lot of it depends on the size of the pattern and a steady hand. When I did this Bonaparte bust years ago a spent hours just free hand drawing the hexagonal pattern on paper at the same size it would be on the bust just to get used to it and a bit of muscle memory. I then drew it on the figure with a feint pencil line after the background painting had been done.
After a few rubbings out when bits didn't look right to the eye I then lined it in with the paint which was probably quite dilute so I didn't get any tramlines from thick paint.
Also to bear in mind that when you get folds and overlaps in cloth the pattern disappears and then comes back so may won't always appear as you see in your pic.............dom

How do people feel about home made transfers for such effects (at least to get the basic groundwork in place)... or do 'we' see that as 'cheating'? (our aircraft and AFV modellers don't)

Neil

BTW: about 40 years back I did a 1/35 or something WW1 German Albatross (plane not bird) in hexagon lozenge pattern... I don't think my eyesight has recovered yet

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