how often to weigh in

Daily, but thats what works for me. This is debated greatly around here.

I used to weigh every freakin' day and get so frustrated by the fluctuation of it. My weight has always been within about 15 pounds since I was in high school... Between 135 and 150, always. I don't gain weight very easily (probably because of my height), but I don't lose it easily either. I also have digestive issues that can add a pound or so depending on indigestion for a day. When I weighed daily, it would go something like this:

Day 1: -0.2 pounds
Day 2: +0.1 pounds
Day 3: -0.4 pounds
Day 4: +0.2 pounds

Drove me CRAZY! So now I weigh once a week and just deal with the curiosity in between. I actually look forward to the day I weigh because I know it's not going to be annoyingly jumpy like it used to be.

I usually weigh a few times a week. But I just update it on here once a week.

I weigh in once a week and sometimes even less.
I weigh in with my personal trainer on the "official" scale the 1st of every month and that's when I update my MFP.

There is no right or wrong. It's whatever works best for YOU.

Once a week!

I get on everyday but I only count it once a week, same day same time.

Don't let the scale rule your life!

I'm with rowb on this one. The problem with weighing in every day is that your body weight can fluctuate from day to day even though overall you are losing weight. Some days you may weigh in extra low (giving you a false sense of excitement) and then other days it may be a little higher. This is why many people recommend that you not weigh in daily because it can get frustrating or cause you to do things that aren't really healthy (like cutting extra calories because you think you're gaining weight).

If you have the personal discipline to be able to look at those numbers and understand that on some days they may be higher than the day before even though your progressing properly and not let it affect your exercise or dieting, then do it. But that takes a lot of trust in your weight loss program to build that discipline and very few people have that trust.

Personally I'd recommend two things. First, don't let weight be your only goal. Have other goals out there that can mark milestones along your route (like fitting into a pair of jeans you couldn't wear before or reducing your waist measurement to a certain point). Your weight, which is truly just a number, should only be one measure of your goals. This will help you see progress even when sometimes your weight number doesn't show it as well. The second recommendation I have is don't weigh in more than once a week. It takes discipline to resist the urge to jump on the scale every day but by doing it once a week you ensure that you'll see the bigger picture of your progress. And if something is going awry, one week is not going to destroy your diet and you can still react quickly to change up your routine as necessary. Remember, this is not a journey, it is a way of life so while we may all want quick results, a few days in the long run won't mean much.