Per the comment on prepping ideas for veterinary needs.

It's an old saw and is in my book, but I also understand that the depth of the concept is frequently not understood. Will your horse do as you ask forward, backward, left, right, up, down or stand still WHEN you ask?

If we even ask this question of ourselves, we get to the do as you ask and then aren't very precise about the answer. But, the second part of the concept is WHEN you ask.

If a horse does what you ask because he was going to do it anyway, or it's convenient for him, or it's not a big deal, no difficulty or stretch, that isn't what we're going for here. Will your horse do it when he doesn't want to?

This takes time setting up situations where you can test horse's responses and test your own skills, observations and knowledge. While you don't need to have the exact experience that you may encounter down the road, it certainly helps if you take every opportunity that arises and make up others.

Taking every opportunity encompasses a lot more from the person in awareness and a lot less of making opportunities. This is because all the little things that horse does that person does not correct/teach are where the opportunities are. A step here, a shift in weight there, put this foot here, no, not that foot and don't shove me with your nose when you're irritated. You can pin your ears and swish your tail, but not for very long. Only as long as I see that you're trying to figure it out. Do you have to? How can you get out of this? You don't understand. Yes, horse those are perfectly fine questions for you to have and contemplate. I'll wait. Well, ready to give it another shot? Well yes, we are working on this. No, not that foot. No, not there. That wasn't it. Nope, not that. I'll wait. But, I'm going to keep asking and only helping you with a small clue every so often if I think you really don't UNDERSTAND. I'm not going to help you much if you're just being difficult because you think you can out persist me.

ALL this can happen just walking over to where you were going to tack up. If you tack up without fixing these slights, they will carry over to the ride where you might have a bit more trouble with them once you're mounted. Even if you don't have trouble that day, when the chips are down or the vet is there or some other crisis arises, right when you really hope that your horse is going to do as you ask WHEN you ask, horse is going to say, "well, I rarely do as you ask, why would I do it when I REALLY don't want to"? And horse's response is right. Why would he? It, of course, is a matter of trust and respect along with time spent earning both that contributes to cooperation and accomplishment.

People just want to get on. Sadly, getting on isn't as much fun as it could be if horse did what person wanted. This doesn't make horse bad or wrong. Not at all. Just a horse. Person doesn't take the time to be precise and horse is aware of every lapse of precision because he gets points for it.

I'm not sure I'm all that fluffy compared to the last post. The same thoughts and issues keep re-surfacing, duh.
When one is first learning to ride and have a horse, there is so much that you don't know. It's impossible to learn it all in a short amount of time. Becoming a horseman takes years, no matter how good your instructor is. And if you don't have a good instructor or you don't have an instructor at all, you could conceivably ride/have a horse for 60 years and still be a beginner rider. While you don't know what you don't know, it's what you don't know that just ain't so that can really get you into trouble.
Who wants to spend a life in trial and error when someone can show you? You're still going to have a lot of trial and error anyway, but most of it will be that if you don't have someone helping you. How many of you would be proficient at math on your own?
Take lessons, read, watch videos, watch horsemen, watch idiots (it's important to learn what not to do!!)

Foundation work
Boy, this is a tough one. People's egos get so in the way of foundation work. Seems it's so much better to canter and stay on and feel that that makes you a much better rider than it is to BE a much better rider by being so good at every level of movement with the horse.

Saddles don't help you become a better rider very fast or very well. People who have ridden for years have no idea how bad their balance is and how NOT with the horse they are because they never sat on a horse bareback. Try it and see. If the horse takes one step and you're swinging all over the place, maybe you're not as good as you should be. If you can't feel comfortable walking on a loose rein all over the place without you BEING all over the place, you're just not that good. And if you feel that you are, then your ego is more important than your riding. And what about trotting or cantering? Ouch. That's harsh. Maybe, but maybe it's not harsh and is just what is.

Maybe I'm cranky today or maybe I've just had a lot of people this week wanting to do things to and with their horse that they haven't prepared for. Either way it doesn't change the issue. The ways of the ego are detrimental to your riding.

Horses, cactus and people.
Most people want to avoid anything that could go badly. Avoid anything that MAY upset the horse. Avoid anything that may get them in trouble. Avoid TRAINING their horse to stay out of trouble. Teaching horses about cactus isn't really that hard. I don't recommend doing it mounted, however, I have on many occasions. Unless you have the stupidest horse on the planet, they are better about the learning than you may think. Don't shove their nose on it, simply present it for them to inquire about. If you've done a good job teaching your horse how to investigate new adventures and objects this goes well in most cases. They also need to learn about as many types of cactus as possible. Horses don't have a cactus book and don't care that it's in the same family. They need to be introduced to all the cactus that you have available or can find.
When your horse is in a frenzy and/or bolting through the terrain is not the time to go "Look out for that cactus." Of course, if he's listening at all (oh, but he's not because he's bolting), he would still be saying "What's a cactus?"
Do your homework before you need it. Get your 12' rope and let them investigate while you're not too close. Or, if your horse is pretty good about knowing that the real estate that you're standing on is never the place for him to be, you can do this right next to horse. But, do do it.