Here's my 2cents:
Train your arms with the big muscle groups to help them grow.
For example, Legs-biceps or Chest-triceps
The idea of this is that when you train big muscle groups such as legs, there is a very large growth hormone and testosterone increase which your arms will benefit from.
You don't have to do the big body part first, you can simply alternate sets between the big body part and the small with plenty of rest. This works for me.
eg Legs, 2mins, Biceps, 2mins, Legs
You could do a total of 5 leg sets and 5 bicep sets. Done.
Do the exercises that recruit the most muscle fibres ie the heaviest weights
eg
Biceps - Barbell curls, Dumbell Curls, Concentration Curls
Triceps - Lying Triceps extensions, Close Grip Bench Press
Do each body part once per week.
Do 6-10 reps per set to failure.