I track weight pretty closely, in grams. Also noting whether the snake its "empty" or not.
I don't measure length regularly. The easiest way to do that is to run a length of string along the snake, them measure the string. The other way is to place the snake in a tube & have it crawl through in a straight line.
I record feeding dates, prey types, and any refusals to feed our other problems. I also record shed dates, and if there are any problems.
The other thing I watch somewhat closely is defecation & urates. To make sure they are regular and on schedule, if there are any problems. That can be one of the first signs of a problem. This is much bigger with some species than with others.
Other than that, I watch behavior, if the animal is acting normally. Alert and active, or active for that species. I also think fecal check ups (smears & floats) are a good idea, especially for new animals.
