I take my measurements once a month or so (officially...I sometimes check it out every couple of weeks). I do my upper arm, thighs, hips and stomach. a lot of people also do chest. I've barely lost any weight but an inch on my waist and 3/4 on my hips so I can tell I'm at least gaining some muscle.
I measure every two weeks. I measure my neck, the thickest part of my upper arms, the top of my chest (around armpits), the fullest part of my chest, the narrowest part of my waist, the very top of my hips (fuller part of my waist, all that belly fat!), the fullest part of my hips (around my behind), the fattest part of my thighs (one side only), the middle of my thighs, and the middle of my calves. I know that's a lot, but it's all the areas I'm really concerned with.
Well I just started, but I will be measuring bust, waist, hips and right thigh (I'm too lazy to measure both, right seemed like as good a choice as left, lol) probably on a weekly basis. I'm weighing in once a week, might as well measure everything, right?
I measure every one-two months. I'm lazy, and don't carry a lot of fat on my upper body so I only measure Thighs, hips (really the biggest spot around which is my butt), and waist (again biggest spot, right below belly button).
Since I started losing (August) I have lost 1 inch on my thighs, 2 on my hips, 3.5 on my waist. I haven't been excercising much recently though.
I try to remember to take mine about once a month, because I would be dissapointed in the small difference that onece a week would give. I check Bust, Waist, Hips, Thighs and Arms. Since I started measuring in Jan 2004 I have lost 3" on Bust, 5" on Waist, 6" on Hips, 3" on thighs and 2.5" on arms