I don't really like using fishing line, seems like it's thin enough to cut through an orchid root to me. I've been using the jute twine that you get at any big box store. It's thick enough and strong enough to hold the orchid in place, and will break down and disappear right about the time the orchid is ready to hang onto the mount on its own. It holds a little moisture, too. Tara says she uses yarn, which seems like a great idea, too.
Here's one I mounted a couple of months ago: You can hardly see the twine on the top, but see it on the back side?
This is my big Schomburgkia cross that I mounted just a couple of weeks ago tied nicely with a twine bow . . . And my three little B. Jairak Kiss plants from our last Apopka run are well attached and putting up spikes on their raft. Oops, there's a black zip tie there - I ran out of twine and that zip tie was handy, it just barely made it around the cork. I can't wait to take it off there, it looks awful.
I always use the cork hanging at an angle, seems more like a tree branch, and holds the water a little bit longer than if the cork was vertical. (might be a consideration for you, Daisy, in your dry environment) Since most of my orchids are hanging up, I like to be able to see the rough outside of the bark, so I mount the plant on the inside. Did it the other way with my huge old raft of "maybe Yellow Bird" and you can't even see any cork now.
There's a post on the previous page where I showed some neat little screw eyes that I attach the hangers with.