I just started messing with acrylic myself. I have found weld on 4 to be the best. Many times it will discolor the acrylic if it gets on an area where other than the seam. But, if this happens just take a small torch or heat and go over the discolored area. This will fix the issue easily.

Also, I have used a small craft paint brush to apply it, this process seems to work best for me.