I don't really cut down on certain things before weigh in as I want a true reflection of my weight and not just a weight because I purposely made myself lighter by doing things a little differently day before weigh in.
But that's just me, my advice would be to:
• cut down on sodium the day before, keep it low
• keep the carbs low
• don't eat too much processed sugar
• drinks lots and lots of water, and then more water
I do all of the above every weekday anyway (apart from the carbs, my diet always has more than 150-225g carbs a day even day before weigh in).
For the first 2 months of losing weight I used to be the one who made herself lighter purposely especially for way in and I also (and I DO NOT recommend this) used to not drink anything at all before weigh in (I weigh at 6.30 in the evening as this is when I got weighed when I was on lighterlife). I would purposely dehydrate myself to weigh less, it worked but I felt really really awful and as soon as I drank it came back on. I am guessing you weigh morning though so I don't have to worry that you will do this he he.
I lost 100lbs overall and lost the last 3 stone 2lbs by good old calorie counting and keeping my processed sugar and sodium down every day. I still eat sweets, cake or choclate but only a small amount.