I'd love to know this as well! The e books are very helpful.

Nice! Personally I like to really dissect the figure when I study anatomy. Eventhough it's not visible on the surface, I like to lightly indicate the deltoid going all the way to it's insertion at the humerus, to be sure it's anchored. You could try that too if you want. Hope this helps :)

Hey, Kevin Nice exercises. Overall they are well done, but there's a few things you can improve: Line weight - The division between the lateral and the posterior head is not clear cut in the majority of cases. A constant line and even divisions may lead to a boring and text book look Varying the weight of the line may improve the overall aspect and give a more natural look. Design - Overall I fell you're constantly designing the heads as inverted tear shapes. Also I feel that sometimes you're using the same curve in the biceps and triceps causing a bit of the snowman effect. Think about the flow other pose and if the muscles are contracting or stretching, vary the shapes and contrast your straights with curves. The arm has a real particular flow to it so be very mindful of that and how it can improve and balance your designs. Cross contours - Finally, Whenever you're doing this kind of study you don't need to always indicate the core shadow. In fact, always seek the most efficient way to represent the pose. When you have a leg or an arm going away or towards you it's easier to indicate it with cross contours to show the perspective than to indicate the core shadow. The first exercise suffers with this problems. It looks like you shortened the arm instead of showing that it's going away from us. Also, remember that you can use the border of the deltoids as a natural cross contour to show the cylindrical form of the arm. Best Regards