Weighing yourself only once a week is wicked smaht. Too many people get caught up in day to day weights and don't realize that their weight in the morning may be different than in the evening, that their weight is different if they've pissed or shit or if they haven't, etc. I'd recommend no more than once a week, but I actually do a once every couple of weeks or once a month.
I recommend taking pictures as well. Change comes so slowly that it's hard to notice, but when you have picture from a month, three months, a year ago, etc. it's surprising.