Well if you have a 6 then you just have to make sure your diet is tight because you don't have much fat to lose.
Sweating is a good option but there is a couple things. If weigh-ins are the night before, that is great because you can cut more weight the day before and have plenty of time to rehydrate and not be as tired from cutting water. If not, just make sure you space out the water cutting sessions.
What I have done in the past and now is trash-bagging it with cardio and sauna. If you do cardio, stretch out first, you are depleting water and if you don't stretch you will cramp up fast. Warm up with a moderate jog then sprint for 30-60 seconds just to get the heat going. After that it is a very slow jog and the sweat will come. DO NOT RUN. After the sprint you should be breaking a pretty good sweat, running will only hurt you. Another thing is listen to you body. If you are feeling faint then STOP IMMEDIATELY. If you over do it, you will hurt yourself. With the sauna just sit there.
Usually my weigh-ins are the same day as my competitions so I start cutting water 2-3 days out. First day is very little water, half gallon, and 30-45 mins light cardio. Second day is 60 mins light cardio and 15-20 mins sauna sipping water. If I opt for a third day I do the same as the second day just no water in the sauna. I haven't been able to get into sodium reduction yet so that is something I can't answer for you now.
One thing you do not want to do is strait cardio with trash-bags to cut weight. I did this before and my calfs cramped up very bad during one of my grappling competitions.