Ditto for the adapter and B+W and Heliopans. I suggest a yellow, light green and/or green and light orange and/or orange. You might consider Proxars or the B+W close-up + diopter lenses if you want something of a macro capability. There are filters for almost any affect. Start with the adapter and the filters you already have keeping in mind their size because if you adapt down (or up too much) it could cause vignetting.

http://www.jeffreyglasser.com/