Bentonite isn't very good after fermentation. You need to keep stirring 2-3 times a day and risk ruining your wine. Gelatin or Sparloid in conjunction with Kieselsol work extremely well (you see some of these supplied in the better kits).
My personal favorite additive is gelatin (I don't use bentonite at all) because it's cheap, really easy to use and changes the finished product the least. Actually time and refrigeration is what I use almost exclusively. I have a batch of Zinfandel that's only 5 weeks old, but it's crystal clear because the basement floor is so cold and it's been sitting perfectly still for about 2 weeks.
Another famous clarifier is egg whites. 1 egg white will clear a 6 gallon batch. Just beat it a little with a 1/2 cup of the wine, then mix it into the secondary. This is the old world additive for clearing up reds during barrel aging.
I hope this helps!