OK, you asked for PRACTICAL methods. Certainly mirror/waistline measurement is the most practical, as anybody can do this at home. But you have to realize the limitation - hold a little more water that day, and suddenly your depressed because you think you’ve “gained” 5 lbs of fat. Can very easily happen after your cheat day, especially if you cheated on pizza.
Second for practicality is those incredibly stupid Tanita scales. They are incredibly inacurate for guys like us. But, if used under the same circumstances over a period of time, by people who are above about 10%, they show a good enough trend.
Calipers are quite practical, if you have an experienced person doing it, and they use enough sites. 3 (which is what most people use) is simply WAY to little. I think you need at least 9, and I’ve heard of people doing up to 12 sites. These seem to track pretty well to under-water analysis.
BTW, one thing that’s not covered is how much is water, how much is real muscle, and how much is skelatal tissue/bone. Check out an article in American Journal of Clinical Nutrition called “Total-body skelatal musle mass”. It presents a predictor using three girth measurements and three skinfold measurements that is supposedly very accurate for most people except pro-bodybuilders or people in that type of shape. BTW, they contend that the absolute most accurate is MRI analysis - talk about expensive and un-practical!