The main thing , or the second main thing with regular weighing is to understand how water levels in the bloody fluctuate all the time. If you understand this then you will know that the morning before food is the best most steady time to weigh yourself. And you'd understand that there's really no point weighing yourself throughout the day.
Water levels are affected by things like hormones and your period cycle, the amount of salt you have in your meals, how much exercise you've done (and sweated out a lot of water) or how often you drink and whether you are dehydrated. Also when you do a lot of exercise or physical labour one day, the next day you can often show a weight gain. This is because muscle building seems to hold more water. And it is mainly only water. And if it were muscle (which is safe to assume after exercise) then you shouldn't be depressed by a weight gain.
So even on a daily basis your weight will go up and down quite erratically based on the water levels of your body. So what you want to be watching for a is overall steady decline.
Also the occasional slip up on a diet is not going to show immediately necessarily. This is because food is not converted to fat straight away. So you have time to burn off all those calories before they are converted to fat. In the meantime it will be stored in your muscles as glycogen. Its liquid energy readily available. I think it takes about 72 hours for excess calories to be converted to fat.
Anyway its great if you can patiently weigh yourself once a week but you could be unlucky and weigh yourself on a high water retention day and feel let down if the scales up not down. If you eat take away foods, particularly any asian packaged foods, you can be sure that your water retention levels will be high. Most fast foods are high in salt and this will keep your water levels high. Its not fat calories its just water which has no calories. And water is easily lost.
I used to weigh myself daily. Nowadays i weigh when i feel like. I'm trying to weigh less, trying to be a bit less obsessive because now i know what works for me and trust that what i'm doing is the right way for me to lose weight so i have confidence and don't get fixated on the scales.
Height - 165cm
Starting weight - 7 March 2013 - 83.6kg
weight - 21 March 2013 - 79.8kg
latest weight - 28 July 2013 - 77kg