Re: Any ideas ?
Do lots of desensitisation to random objects. Wheelbarrows, umbrellas, matresses, wheelie bins, tarpaulins, road signs, ditches, anything you may come across. Learning for itself is a great way to boost a horses confidence, if they can work out something isn't scary on their own instead of following another horse to do so then they'll be braver for it.
Do lots of gate practice, ie. opening and shutting while on board. Get on and off from both sides. Find water (stream, sea, etc.) and ride through it in all paces, jumping if you've got that far.
I love doing fancy dress, and it's great fun on horseback. I made a jousting outfit for my horse. It went on over her head and I had a sheild and a huge lance. Being a relaxed cob, and rather a softie, and me being a nice person she wasn't even remotely fazed, even as I was waving the lance and running around her!
Good luck and have fun!!