>>And if anyone has tips on getting good head shots on these guys please spill!
there are good tips here from others, too. but try this: learn the camera controls on an inanimate object, not while you're wrestling with a squirmy snake. Practice getting good lighting and focus by taking pictures of your cellphone, or a fork, or a golf ball, or.... Use that practice to figure out where your camera is set to focus (small spot in dead center? averaging the whole frame? most cameras allow you to choose from those or other options) Where do you get the best lighting? What method enables you to best hold the camera steady? What part of the camera's zoom do you use? Most macros focus extremely closely only in wide-angle mode; when you start zooming in (using telephoto function) the distance from subject increases considerably.
As noted by others, the brighter the light, the faster the shutter speed, thus the sharper the picture, PLUS the more of the subject will be in focus: in dim light, at the camera lens's widest opening, your "depth of field" might be a fraction of an inch, and you want more than that.
And remember your camera's meter is reading the light on the subject, just as it reads the focus, depending on how it is set: is it reading a small spot dead center? picking an exposure setting that'll work best for the average part of the whole frame? If you have a snake that's neither very light nor very dark colored, and you try to photograph it against a background that's either of those things, the background will probably throw your exposure off, unless you have it set to read dead center and point that part of the frame at the snake.
Do you know that with most cameras you can depress the shutter half way, when you've got the focus & light right, and the camera will hold those settings until you press the rest of the way? That way, you can focus on the snake's head (in the center of the frame, for ex, if you've set your focus that way) and then move the aim slightly left or right, to show some coils of the animal, and the head will still stay in focus.
By the way, I liked your ground-level pic of the snake. NOthing wrong with the head being sharply focused and the coil closest to the camera being blurry. In fact, that directed attention nicely to the snake's head, which is the real point of interest.