When I had added beads, wire etc., to all my peices, I added a few micro beads here and there (with Dimensional Magic as a glue).
When your beads are dry, hang the charms off the peices with a jump ring.
And finally... with good strong glue (I use Weldbond its brilliant) glue the pin or magnet to the back of your peices, as high up as you can position it.
Tip: open the jump rings with your needle nose pliers by twisting the ends apart, one end towards you, one end away from you. Never PULL them apart. They will close up much neater if you just twist them apart. Once they are pulled apart with a gap in the centre, its hard to keep them round.