The more you do it the better they get. I found it helpful to approach the head from the neck, with the nozzle set on stream, not on spray, so that the flow was more gentle, or take off the nozzle and just have a gentle flow, not a high-pressure torrent of water. Then I hose off the lower neck, work my way up with the nozzle next to the horse (even letting the hose lay against the skin which works well if you don’t have a spray attachment/nozzle) as I wash with the other hand. When I reach the upper neck and ear area I just let a quick drizzle wash over the poll onto the face. Even if they toss their head (which they will) you just ignore it and keep on washing with the other hand holding a rag, quickly running it over the forehead down the front, sides, etc. One or two more douses with water and you have enough to do the job. So basically, you just matter-of-factly wash them and don’t stop because they fidget or avoid, but you do give the one concession that you make the face rinsing quick so that it doesn’t become a big, unpleasant (for both of you) fight.
Oh, I also didn’t tie my difficult horse when bathing because I didn’t want to get into any unpleasantness with her pulling back and feeling trapped. Instead I made her stand, by doing the thing where you don’t stop the water on them until they stop fidgeting and backing or moving. It worked really well and she learned quickly to behave. (Although I am a bit klutzy with holding the hose, a lead rope and a rag. I usually ditch the rag until the rodeo is over and just hose them). Also, if you hose them for a while on a hot day, they eventually realize they are enjoying it and then you can start the sneaky quick over-the-poll rinses.
It’s kind of like handling their ears when you get a horse that doesn’t like having his ears touched: you touch the ear quickly while grooming, maybe run your hand or brush along it every time and then you increase the handling and touching each time you groom and pretty soon you have a horse which cocks his head and groans with pleasure when you massage his poll, pull on his ears and scrape the bugs and itchy things out.
I like Palm Beach’s mist technique too.