Put some 'permanent' scary things in their field. For example a flag in a cone. Plastic sheet pinned down to look like water tray. This way they can sniff and explore things at their own pace, in the 'safety' of their own field.
Also, if possible put them in field next to road so they can get used to traffic.
I have one of the spookiest horses on the planet. It was obvious at age 3, when I got him, that he was going to need much work, so I spent many hours rattling things near him, rustling plastic bags, good old-fashioned 'sacking out', wrapping ropes round his legs, making him walk on and off tarpaulins, walking round the farmyard where he met tractors, cattle, sheep, big bales, flapping black plastic, drainage pipes. I waved brushes, opened umbrellas, played loud music, splashed through puddles.
None of it did any damn good. But there is a very good book 'Bombproof your horse', available on Amazon, and that did give me lots of ideas, even if they didn't work in my case!
Re competing, I took him to a nearby endurance event just to let him have a look round, meet the farrier, have a mock vetting, see all the trailers coming and going. That was successful, as the first time we went for real he behaved beautifully.
TBH I find normal life is enough for them (unless you have a parelli type affliction).
I tend to take my youngsters out when I'm walking the dog and they practise walk and trot in hand (some also practise trying to kill the dog
) They see a bit of life, a little bit of roadwork and you get some sneaky in hand schooling done into the bargain.
The best education though is to take them to lots of shows on their own - they tend to 'need' you more if they're on their own rather than screaming back to the buddy that you've left on the lorry.
Thats a good idea. Kill two birds with one stone, as they say! Im sure the dogs wouldn't mind
I have managed to take her to 3 shows since I have had her so she has had some ringcraft practice and lots of scary things to contend with. I just want to do as much as poss before I start competing on her back!
2nd the walking out. Dolly went on lots of walks as a 2yr old. Sometimes, I did ride another more experienced horse just in case, but luckily when the scary milk float was hiding round the corner & my 19yr old was prancing round like a loony, Dolls walked past meaning I could follow!
We've done clippers & plastic bags, but I think the desensitisation could have backfired as she is now desensitised to my leg.
I've been walking Piper out as much as the weather allows. We have very busy (but not fast cars) housing estates around us, as perfect for letting him see everything and anything.
I take him out with the older, already totally bombproof horses, but peel off to come home on our own when they go for a proper ride.
I ride out with my 30yr old by the side of my youngster. She is really great and doesnt flinch at a thing....I also allow my youngster to take his time with things he is not sure of, followed by gentle voice and patting. He does really well.....
I tend to put things out in the field too for him to get used to - so bags in bushes and trees - cones etc...he soons gets used to them and is ok about it....