If on a horse, treat the w key like a car accelerator. If you want to coast for a while, you can by taking your finger off the w key. If you want to turn sharply, again, take your finger off the w as you turn and maybe even press and hold the s to decelerate as you turn.
It's all muscle memory that will come with time.
Don't even start me on learning not to spam the sword thrusts.