Hey Jay.
I had similar problems when I first started tying the knot as well and found this to help a little:
Make sure that your spool of leader has one of those line keeper covers, or use an elastic band or something and only pull out a short section of leader ( enough to wrap around your finger on your right hand when you start the knot, know what I mean? ) and enough for the area you are tying the knot.
Then while you are tying the initial "loose" wraps of the knot, winding down, allow the spool of leader material to hanging free on a short bit of the leader, it will spin a little while you are wrapping but not too badly.
Then beging the tighter wraps as per normal but with as little "tag" end as possible, so that all your leader is still sitting on the spool. The whole spool itself might spin quite a bit while hanging free, but you won't get as much actual line twist in the leader itself...
I'm not sure if I'm explaining quite right, and it may not be a total preventative method, but it helps some.
The other reason may be that your bobbin is set up too tight while wrapping... I know you want it as tight as possible to create a good bind, but if its too tight, especially with not enough weight in the bobbin, it compounds the twisting issue I've found.... Heavier the bobbin the tighter you can wrap it round the arm of the holder without issues, but if its too tight, I've had that cause some problems...
Dunno if this will help, but its an idea....
