I've tamed my first horse (a dappled brown and white fellow), and know that after mounting a wild horse, I need to hit 'L' to soothe the savage beast until it obeys my commands. But I can't calm down any of these much more appealing solid coated horses that I see - they all throw me off almost instantly. I've managed to tame a freakin' bear, so I know I'm 'doing it right', but I can't tame a simple black, brown, or grey horse for the life of me. Other than mashing the 'L' button harder and faster (ugh), is there any trick I can employ to soothe one of these horses?
Having more endurance or stamina should help you, as you get thrown off when you run out of stamina. The easiest way I've found was eating energizing foods while taming, since it's possible to stop whatever you're doing to gobble up something. You can cook a few Stamella Shrooms on their own or make an energizing elixir, anything that will restore more than a quarter bar, since you want to have time to actually soothe the horse. You can then fill your stamina bar when it gets low, which will allow you to keep soothing the horse until it is tamed. Make sure you have several of those on hand; some horses can take 3 full stamina bars to calm down.
If you have access to enduring foods or elixirs, they should work well too, as your stamina won't go down as fast, giving you more time to work with. However, you may still want to have stamina restoration consumables on hand.