There are plenty of guides to cutting weight out their on the internet. The best advice i can give you is to not try to cut to much. Personally, when i was fighting MMA, i didn't really cut weight. I would diet a little bit, but never got into the whole cut 15lbs of water weigth and hope to get properly hydrated in 24h. It's not good for your performance, it's not good for your kidneys, and the rest of your body either.
Now. if you want to cut weight anyway... the basics is this: the week before, drink lots and lots and lots and lots of water. this get's your body thinking yay i've got so much water i'll just pass it right through. then the day before weighins, only drink when your thirsty, day of weigh ins don't drink at all. at least 3 days before cut out all sources of sodium.
day of weigh ins, find a suana, sit in it. for as long as you can stand, then take short breaks. some people like to wear a lot of layers in the sauna, some like to go nude. some take a credit card or something similar, and scrape the sweat off their bodies with it. the theory is that sweat evaporating is how you body cools off, so if you don't let it evaporate, you'll stay hotter, and sweat more.
there are other theories like shaving your whole body right before will open up your pores and make you sweat more, 2 fighter friends of mine swear by this. but i haven't tried it.
depending on your weight, you should probably be able to cut 10lbs of water weight with just the super hydrating and sauna. of course if your only 125, it's probably less the that. and if your 250 it's going to be more.